A powerful gas blast ripped through a four-storey building in Prague's historic centre on Monday, injuring 43 people including foreigners, and causing panic in the Czech capital.
Rescuers had feared there could be bodies trapped under the rubble of the heavily damaged office block, but the city's mayor said nobody was believed to have been killed.
The force of the explosion damaged parked cars and two adjacent university buildings, blew out windows in nearby streets, and shook apartment blocks across the Vltava river.
"It was a gas blast, not a terror attack," Prague mayor Bohuslav Svoboda told reporters.
He added that "they haven't found anyone (in the rubble)... and nobody is reported missing".
"It was a terrible blast, everyone was awfully scared," a woman working at the adjacent journalism faculty of Prague's Charles University told AFP, declining to give her name.
"Everyone was running, the blast toppled the bookshelves in the library. In one classroom there were lots of injured students, the librarians had blood on their T-shirts," she added.
"At one department the blast wave broke a window on one side and warped the door on the other so people couldn't get out and had to kick the door open."
Forty-three people were injured, including two Kazakhs, two Portuguese, one German and one Slovak, said Zdenek Schwarz, head of Prague emergency services.
Police sealed off the popular tourist area and evacuated 230 people from nearby buildings, fearing further gas leaks, Prague police spokesman Tomas Hulan said, adding that several hundred officers were called into action after the explosion.
An AFP photographer at the scene saw dozens of people with cuts from shattered glass from windows along the debris-strewn Divadelni Street.
Injured victims were treated on the spot for cuts, some with blood streaming down their faces and bandages on their heads and many of them in shock.
Jan Hora, a structural engineer, told Czech TV the damaged building -- a former block of flats now used as office space -- had to be supported with poles but would probably not collapse.
The force of the blast shifted the wall of the building by about five centimetres (two inches) and Hora said it likely occurred on the ground floor, where the ceiling was destroyed.
"The initial gross estimate of the damage (to the building) is 10 million koruna (390,000 euros, $510,000)," Jiri Civka, spokesman for the Generali insurer, told the CTK news agency, adding that it would rise if the building gets torn down.
The area's architecture mostly dates to the 19th century and includes the ornate National Theatre, whose modern section was damaged by the blast.
Prime Minister Petr Necas said in a statement he was "deeply affected by the tragedy" in the capital, which welcomed more than 5.4 million tourists last year.
An unnamed student told Czech TV that students and teachers from nearby universities panicked and ran out when the blast shook their buildings, fearing a terrorist attack.
"Blast in Divadelni (street), many injured. Windows broken at journalism faculty," Milos Cermak, a journalist lecturing at one of the universities, wrote on Twitter.
"Police say gas still leaking. Helicopter above us. Classes cancelled for rest of week."
Vitek Novak, a journalism student, said he saw several students cut by glass.
"We were sitting at school and then we heard a tremendous blast, all the windows broke. I was lucky to sit farther from the window," he told the DNES newspaper.
In a similar incident in France on Sunday, three people died and 14 were injured in the city of Reims when an apartment block collapsed after a suspected gas explosion.