(CNSNews.com) - The British government was slow to release information following a series of coordinated terror attacks in Central London on Thursday, and cable TV stations scrambled to get the latest details, even as bombs kept going off.

A number of simultaneous explosions rocked -- and apparently still are rocking -- the city's transportation infrastructure, a scenario some are comparing to Madrid.

The first series of blasts hit the London subway system toward the end of the morning rush hour, around 8:50 a.m. London time (4:50 a.m. EDT). Press reports put the number of subway explosions at five.

One explosion tore apart a double-decker bus -- maybe as many as three, press reports said.

It's still not clear how many people were killed or injured, but the number is expected to be high. Ambulances were having trouble getting through traffic-snarled streets.

Police initially blamed a "power surge" for the London Underground explosions but they did not rule out terrorism, which looked more and more likely as additional reports of explosions kept coming in.

One witness was quoted as saying that he saw the top blow off a bus; and subway passengers said they heard explosions before the power went out on the Tube.

The London Underground is now closed, and central London, where the explosions happened, is a scene of mass confusion.

British officials were urging people to stay inside and off the streets.

Just yesterday, London was in a celebratory mood, after learning it had won a competition to host the 2012 summer Olympics. And Thursday's attacks come as Prime Minister Tony Blair is hosting world leaders at the G8 meeting in Scotland.

He was expected to speak shortly.

More to come.