The vast glass roof covering a Moscow water park collapsed today, killing at least seven people, injuring nearly 70 and trapping others under the rubble, Mayor Yuri Luzhkov said.

Initial reports said the roof at the Transvaal water park had collapsed after an explosion, but officials including Luzhkov later said there was no evidence of an explosion.

Some suggested the collapse could have been caused by an accumulation of snow.

“There was a loud noise,” an unidentified witness told Russia’s Channel One television. “Everybody started to run. I started to run. All of the roof over the zone of water collapsed.”

In footage from inside the park, the NTV television station showed beams apparently made of concrete had fallen on the park’s twisting water slide.

Luzhkov said rescuers heard voices from under the rubble at several points and rescuers were working to pull victims out, the Interfax news agency reported.

He said 69 people were injured and other officials were quoted as saying about 40 of those had been hospitalised.

The collapse happened about 7.30pm (4.30pm Irish time) as the Transvaal water park in Moscow’s south-western suburbs was filled with hundreds of people, basking in its heat while temperatures outside hovered around minus -15C (5F).

Despite initial reports of an explosion, city police spokesman Pavel Kleimovsky was quoted by ITAR-Tass later as saying accumulated snow was the apparent cause.

The Russian capital has been on edge since the February 6 bombing in a Moscow subway that killed 41 people and wounded more than 100.

President Vladimir Putin blamed Chechen rebels for that attack.

The radio station Ekho Moskvy said that some of the customers at the park fled outside into the frigid temperatures clad only in swimsuits.

ITAR-Tass said about 600 customers were at the park at the time.

The water park is one of several flashy entertainment facilities that have opened over the past couple of years on the city’s outskirts.

It includes a large pool, an artificial river and a lengthy water slide.