By Michael Sheils McNamee in London and Jenny Hill and Michael Steininger in Berlin
The atrium of the Radisson Blu Hotel in Berlin lies in ruins after the AquaDom aquarium, which stood 15.85 metres high and was home to 1500 fish, burst. Photo: dpa Picture-Alliance via AFP
A giant aquarium containing a million litres of water in the lobby of the Radisson Blu in Berlin has burst, flooding the hotel and nearby streets.
The "AquaDom" - home to 1500 fish - is 15.85m high and was described as the largest free-standing cylindrical aquarium in the world.
Two people were injured by falling glass after the blast.
Police said there had been "incredible" damage. Video showed an empty tank with water pouring into the hotel lobby.
Guests have been moved out of the hotel following the incident at 5.50am local time.
A spokesman for Berlin's fire brigade told the BBC the vast majority of the fish had died, while the cold weather had made rescue attempts more difficult. The tank had contained more than 100 different species.
The AquaDom aquarium in December 2003. Photo: DPA Picture-Alliance via AFP
However, fire brigade official James Klein later told local media that "several dozen" fish had been found alive in places where residual water had collected. He said they were being rehoused in other aquariums.
Also, the Associated Press quoted officials as saying they were working to rescue another 400-500 fish in smaller tanks under the hotel lobby which had been deprived of oxygen because of the disaster.
Outside the Radisson Blu, a pile of debris lay in front of what were the front doors, which now hang into the street - twisted at an angle by the force of the exploding tank.
Paul Maletzki was staying on the fourth floor with his girlfriend.
He described being woken up by a loud bang and shaking. When he looked down into the lobby, he saw water flowing across it. They and other guests were later escorted out of the hotel by armed police.
The Mayor of Berlin, Franziska Giffey, went to the hotel to see the damage and described the tank burst as being like a tsunami.
She expressed relief it had happened so early in the morning - saying an hour or so later, and the lobby and street outside would have been busy with visitors, many of them children.
Sandra Weeser, a member of the German federal parliament who had been staying at the hotel, told local television that she had been woken up by "a kind of shock wave" and described the scene outside the hotel as a "picture of devastation".
She said fish which may have been saved had frozen to death and recalled seeing a "large parrotfish lying on the ground, frozen".
The aquarium was modernised two years ago, and there is a clear-walled lift built inside for use by visitors. Some of the rooms in the hotel are advertised as having views of it.
Berlin's fire brigade said more than 100 firefighters were sent to the scene and it was not clear what caused the break.
It said it used rescue dogs to check the area inside the hotel for anyone potentially injured, with nobody found.
Debris strewn in front of the Raddison Blu in Berlin after the 15.85m aquarium in the hotel's lobby burst. Photo: DPA Picture-Alliance via AFP
Police said "massive amounts" of water were flowing into nearby streets and people in the area should drive cautiously.
A police source told local media there is no evidence the break was the result of a targeted attack.
But there has been speculation that freezing temperature - which dropped as low as -6C overnight - may have caused a crack in the tank.
Berlin's public transport authority said Karl-Liebknecht street outside the hotel had been closed off due to "an extreme amount of water on the road". Tram services in the area were also stopped.
AquaDom was opened in December 2003 and was given the Guinness World Record for being the world's largest cylindrical aquarium.
According to reports at the time of its construction, it cost about €12.8 million ($NZ21.3m) to build.
- BBC