Journalists attempting to cover unprecedented unrest in Egypt reported being targeted, beaten, arrested and harassed by security forces and police for a second day Thursday.

Al Jazeera released a statement demanding that three of its journalists, detained by Egyptian security forces, be released. A fourth has been reported missing, the network said.

The Greek daily newspaper Kathimerini said its reporter, Petros Papaconstantinou, was beaten by protesters in Cairo's Tahrir Square. Papaconstantinou was clubbed in the head with a baton and stabbed in the foot, either with a knife or a screwdriver, said Xenia Kounalaki, head of the newspaper's foreign desk. A photographer also sustained minor injuries, Kounalaki said, and both were treated at a Cairo hospital and released.

The Washington Post reported, citing multiple witnesses, that its Cairo bureau chief, Leila Fadel, and photographer Linda Davidson were among two journalists arrested Thursday morning by the Egyptian Interior Ministry.

"We understand that they are safe but in custody, and we have made urgent protests to Egyptian authorities in Cairo and Washington," the Post said on its website. "We've advised the (U.S.) State Department as well."

"Situation on ground in Egypt very tense," CNN's Anderson Cooper tweeted Thursday. "Vehicle I was in attacked. My window smashed. All OK."

Other journalists reported close calls. Marie Colvin of the Sunday Times of London said she was approached by a gang of men with knives in Imbaba, a poor neighborhood of Cairo. Another group of men, who also were strangers to her, pushed her into a store and locked it to protect her, she said.

A photojournalist for CNN-IBN, Rajesh Bhardwaj, was detained in Cairo's Tahrir Square, the site of bloody clashes between supporters and opponents of President Hosni Mubarak. He was taken away by the Egyptian Army and later released, but only after his identification card and tapes were destroyed, said Suhasini Haidar, CNN-IBN deputy foreign editor.

The Indian Ministry of External Affairs was advising Indian journalists in Egypt to avoid trouble spots.

In addition, Amnesty International and Human Rights Watch each reported one of its representatives was detained by police in Cairo after the Hisham Mubarak Law Center was taken over by military police.

Human Rights watch researcher Daniel Williams, an Amnesty International researcher and several others were taken into custody, the groups said. The monitors were interrogated at the center before being taken away in a microbus, Human Rights Watch said. Amnesty International reported they were taken to an unknown location in Cairo.

"We call for the immediate and safe release of our colleagues and others with them who should be able to monitor the human rights situation in Egypt at this crucial time without fear of harassment or detention," said Salil Shetty, secretary-general of Amnesty International. Other activists were still being held in the center, it said.

The New York Times reported Thursday that two of its reporters had been released after being detained overnight in Cairo.

And the BBC tweeted Thursday, "Egyptian security seize BBC equipment at Cairo Hilton in attempt to stop us broadcasting."

Al Jazeera said Thursday that six of its journalists had been detained by Egyptian authorities in the past week, with equipment stolen and destroyed. "It has also faced unprecedented levels (of) interference in its broadcast signal across the Arab world," the network said in a statement.

A spokesman for the United States blasted forces in Egypt Thursday who have harassed, detained and beaten journalists.

"There is a concerted campaign to intimidate international journalists in Cairo and interfere with their reporting," U.S. State Department spokesman P.J. Crowley said Thursday on Twitter. "We condemn such actions."

U.N. Secretary General Ban Ki-moon condemned the attacks.

"The freedom of speech, whether journalists or demonstrators -- they should be fully guaranteed and protected. That is a ground principle of democracy," he said.

Meanwhile, Shahira Amin, a reporter for Egypt's state-run Nile TV, resigned Thursday.

"I spent the day at Nile TV yesterday," she told CNN. "I was only allowed to air the pro-Mubarak rallies that were going on, as if nothing was happening at Tahrir Square. We weren't allowed to reveal any figures. There was a near total blackout," she said, calling it "hypocritical ... I just don't want to be part of it."

She said she should have resigned "ages ago. ... I was happy to spend the day in Tahrir Square where the people are. ... I am on their side."

Journalists were also targeted on Wednesday, with some beaten, bloodied, harassed and detained by men, most of them apparently aligned in some way with Mubarak.

Numerous news outlets -- including the BBC, ABC News and CNN -- reported members of their staffs had been attacked, mostly on the streets of Cairo. In several cases, news personnel were accused of being "foreign spies," seized, whisked away, and often assaulted.

"It was pandemonium. There was no control. Suddenly a man would come up to you and punch you in the face," said CNN's Cooper, describing being attacked by pro-Mubarak demonstrators along with two colleagues outside of Tahrir Square.

CNN's Hala Gorani got caught Wednesday morning in a stampede of demonstrators, some of whom were riding on camels and horses.

"I got slammed against the gates and was threatened by one of the pro-Mubarak protesters who was ... telling me to 'get out, get out!'" Gorani said. "The pro-Mubaraks, whoever they are, whoever sent them, are being threatening toward camera crews, journalists, anybody who looks like they may be onlookers."

A BBC correspondent, Rupert Wingfield-Hayes, and his crew were "arrested by members of the secret police" on Wednesday after interviewing a presidential adviser, the BBC reported. They were later released, the network said.

The Dubai-based Al-Arabiya news network was among the worst hit, with its office damaged and several of its staff targeted. Among them was correspondent Ahmed Abdullah, who his editor confirmed Wednesday was found bloodied and transported to a hospital after being severely beaten by his captors.

Maurice Sarfatti told the Brussels-based Le Soir newspaper, which he writes for along with publications in Switzerland and France, that he "received a steam of blows to the face" from men claiming he backed leading opposition figure Mohamed ElBaradei.

"I am being guarded by two soldiers with Kalashnikovs (rifles) and bayonets," said Sarfatti, according to a translation from Le Soir. "They say I will be taken before the intelligence services. They say I am a spy."

The Committee to Protect Journalists, a New York-based advocacy organization, claimed that such accounts were all too commonplace around Cairo.

In a news release, the group detailed about a dozen incidents, accusing men -- most of them described as pro-Mubarak demonstrators, "plainclothes police," uniformed officers and military -- of perpetrating attacks on reporters seen with cameras and notepads.

The group laid the blame for this violence squarely on Mubarak's administration, accusing it of scheming to suppress and stifle news coverage.

"The Egyptian strategy is employing a strategy of eliminating witnesses to their actions," said Mohamed Abdel Dayem, the committee's Middle East and North Africa program coordinator. "The government has resorted to blanket censorship, intimidation and, today, a series of deliberate attacks on journalists carried out by pro-government mobs."