© Omar Sobhani / ReutersAfghan policemen keep watch near the site of a blast in Kabul, Afghanistan August 1, 2016.
The blast occurred in the middle of the night, at around 1:30 am local time. The blast has been described on Twitter as being so loud that it woke up people "all over the city."
A "truck bomb" struck "a foreign guesthouse," reported Lotfullah Najafizada, head of Kabul-based TOLOnews TV broadcaster, citing security sources. He added that "four attackers" were trying to enter the building.
"A truck full of explosives exploded near the entrance of Northgate [hotel]," reported Bilal Sarwary, another local journalist, citing police, adding that there were reportedly four attackers involved.
"Fighting is heard" in the proximity of the site, he added.
The Taliban has reportedly claimed responsibility for the attack, TOLOnews reported. The terrorists allegedly explained that they had targeted the hotel because it is a foreign luxury site located away from civilian homes.
Local security forces have put the area on lockdown and were reportedly fighting several attackers on the ground, Sarwary reported, citing a police officer at the site, who said that "sporadic gunfire can be heard every 10-15 minutes."
"Foreign special forces" have arrived at the attacked compound along with local elite military units, TOLOnews reported.
Afghan forces are preparing to storm the building, as it is believed that the perpetrators could still be inside, it added.
No information was immediately available on the number of casualties caused by the attack. Local reporters on the scene said that they saw several ambulances leaving the scene as Afghan special forces continued the operation.
The sound of sirens, "mainly from foreign embassies," was also heard in the city following the blast.
On its official website, Northgate Hotel, which is operated by the Gate of the North Limited company, brands itself a "secure hotel based in Kabul." Apart from providing 24-hour hotel services, the company says it is involved in the construction and logistics sectors.
"Northgate Hotel Security is modeled to military standards implemented by a Private Security Company managed by a highly trained and experienced western force," the company states.
Conflicting reports arose regarding the actual target.
Reports had initially linked the blast to a malfunction in the city's power grid, which was knocked out around the time of the attack, but some witnesses on Twitter claimed that the electricity had actually gone off shortly before, and not after, the explosion.
TOLO news noted earlier on Twitter that a large gas storage facility is located near the blast site in the Pul-e Charkhi area. There was also an unconfirmed report of a rocket landing in the area.
Meanwhile, Reuters cited a security official as saying that the truck bomb had targeted a "compound for foreign military, logistics services," but reported later that he was referring to the Northgate hotel. The agency quoted a spokesperson for the NATO-led Resolute Support mission who said they were assessing the situation, while failing to provide any details.
Several journalists reporting on the blast claimed that Camp North Gate was under attack.
Camp North Gate is located some 40 kilometers from Bagram Air Base and had previously been attacked by the Taliban in 2013. All of the gunmen and several Nepali and Afghan security guards died in that attack.
Kabul has recently experienced a wave of terrorist attacks. On July 24, a huge blast rocked a school in the city's embassy district. As the school's premises were empty at the time, no casualties were reported, although five people were injured by broken glass.
On July 23, however, a twin suicide bombing in the city killed at least 80 demonstrators and injured over 200 at a mass Shiite rally. That attack was claimed by Islamic State (IS, formerly ISIS/ISIL).
Earlier in June, 14 Nepalese and Afghan security contractors were killed in a blast when a suicide bomber attacked their vehicle near Kabul. The Taliban claimed responsibility for that assault, saying it was fighting "the forces of aggression."
Comment: The Camp North Gate hotel reportedly caters primarily to US and other Western defense contractors. Still no word on casualties, but dozens are feared to be dead. Afghan security forces have begun storming the hotel. Recently, the Taliban sent a delegation to China to discuss the situation and their battle against foreign occupation. See: