LONDON, July 9: Police evacuated the central entertainment district of England’s second city Birmingham on Saturday evening after receiving a warning, two days after bombs killed more than 50 people in London.

Thousands of people were being asked to leave Birmingham city centre while police roadblocks on main access routes stopped others from driving in.

“We are asking people to leave Birmingham town centre and go home,” said a police spokesman, who declined to elaborate on the nature of the warning.

The operation was by far the biggest of several security scares in Britain on Saturday in the wake of Thursday’s attacks on London’s transport system.

Earlier, police revealed that the three bombs that ripped through London underground trains went off almost simultaneously, making it more likely they were detonated by timers rather than suicide bombers.

A fourth bomb that blew up a bus almost an hour later was probably left in a bag and not triggered by a suicide bomber, they added.

The blasts killed more than 50 people. Police did not speculate why the fourth bomb went off on a bus, but media and security experts speculated that it had initially been destined for a train.

Investigators were struggling in extreme heat to retrieve bodies still trapped underground two days after the attacks, and anxious relatives were frantically looking for loved ones missing since the rush-hour blasts.—Reuters