© REUTERS / Ed Zurga
A man looks through a friend's trailer as he tries to find anything salvageable after a devastating tornado hit Joplin, Missouri May 23, 2011.
The death toll from a monster tornado that hit Joplin, Missouri on Sunday rose to 123 with 750 people injured and many more missing, authorities said on Tuesday.

Rescue and recovery teams scoured the wreckage of the small Midwestern city, which was devastated by a high-velocity whirl of wind that destroyed about 2,000 buildings.

Forecasters expected new storms to move into the area during the night as a line of tornadoes marched eastward from Oklahoma, where at least two people were killed and many more were injured when a tornado struck west of Oklahoma City. Two more people died in Kansas in storms there Tuesday.

Even so, rescuers in Joplin vowed to work as long as possible through the night searching for survivors. "There is always hope that you will find someone alive," said city spokesman Dan Crain.

Among those missing was toddler Skyular Logsdon, whose red T-shirt and pants were found torn, rain-soaked and wrapped around a telephone pole.

The little boy has not been seen since Sunday night when the tornado ripped through the centre of the town of 50,000 in southwest Missouri. His parents were found alive and were hospitalized, but the family home was demolished and the boy was lost in the whirling darkness.Relatives have mounted their own search, picking through rubble and checking with morgues and hospitals in the hope that he will turn up.

"We still have not heard anything. But we're not going to stop until we find him," said the boy's great grandmother, Deb Cummins.

Authorities said they were racing against the prospect of more bad weather as well as grim survival odds for anyone still trapped after the tornado uprooted trees, twisted cars into heaps of metal and destroyed homes, churches, schools and a line of restaurants and businesses.

In Joplin, authorities said they would search for as long as they could without endangering their rescue teams.

For Kenny McKeel, the search for his lost family is already over. Only hours after the tornado hit, McKeel found his father's body and that of his stepmother laid out on the lawn, their home collapsed around them. The neighbours -- a couple and three children -- also died, he said.

McKeel pulled his father's cane from the debris and tried to hold back tears. "I see this stuff. It means a lot to me," said McKeel. "And it kills me."

Deadliest in Decades

The tornado that hit Joplin with winds of nearly 200 miles per hour (328 km/hour), was the deadliest single twister in the United States since 1947, when a tornado in Woodland, Oklahoma, killed 181 people.

The funnel cloud cut a path nearly six miles (9.5 km) long and up to 3/4 mile (1 km) wide.

"Pretty much everybody in town knows somebody they've lost," said Missouri Governor Jay Nixon.

It was the latest in a string of powerful storms this spring that have killed more than 300 people and caused more than $2 billion in property damage across the United States.

Joplin's tornado likely caused insured losses between $1 billion and $3 billion, according to catastrophe risk modelling firm EQECAT.

U.S. President Barack Obama plans a visit to the south-western Missouri city on Sunday, after he returns from a weeklong, four-nation tour in Europe.

Search efforts have been complicated by bad weather, and two law enforcement officials were struck by lightning on Monday. One remained hospitalized in critical condition.

"This has been totally devastating," said Rich Serino, deputy administrator of the Federal Emergency Management Agency. "This is certainly among the worst that I have ever seen."