BEIJING (AP) _ Hundreds of people were evacuated Wednesday from the massive building that will house broadcasters from around the world when the Beijing Olympics open, fearing there was a gas leak after people inside smelled a strong chemical odor. But authorities later said it was a false alarm and the smell probably came from building materials or chemicals.

Authorities told workers it was safe to go back in and there were no reports of injuries.

John Barton, the director of sport for the Asia-Pacific Broadcasting Union, said he was in his office at the International Broadcast Center when people began running down the halls and telling occupants to clear out. He said no alarm sounded.

"The gas was swirling down the corridor and the emergency drill, if there is one, wasn't followed," Barton said. "Ladies were running up and down the corridors saying 'Get out of the building,'" he added. "I stepped out of my office and I thought it was some kind of joke — no sirens, no speakers, nothing."

Others at the scene also said there was a strong gas smell in the building before it was evacuated. Firefighters went in along with at least one emergency worker dressed head-to-toe in an orange hazmat suit.

But Gao Changli, the executive venue manager of the International Broadcast Center, said the odor came from building materials or liquids. He said there was no gas leak.

The 970,000-square-foot building opened a few weeks ago and is a short walk north of the two iconic venues for the Aug. 8-24 Beijing Games: the Bird's Nest National Stadium and the Water Cube swimming venue. It will house thousands of broadcasters when the games start.