Authorities say at least nine people have died and more than 50 were injured when a well-known office tower caught fire in India's information technology hub of Bangalore. Some of the victims fell to their deaths.

Hundreds of people were working in the seven-story Carlton Towers when an apparent electric short circuit filled the upper floors with smoke.

The ladders of the responding fire trucks could reach only until the fourth floor. Those on the ground held up signs urging those trapped to break the windows, as described by an eyewitness:  

"There was no fire [that we saw] but there was huge smoke," said the eyewitness. "And what happened, we started saying to them 'break the glass, break the glass.' But what happened, people were trying something to convey the message and they took some wrong message. And suddenly I saw the lady, she was trying to escape or something and she jumped out. That was the first instance. And after that people were in a very panicky situation."  

Authorities say five of the people who died jumped from the upper floors. A Bangalore television station broadcast scenes captured on cellular phones showing some of those falling to their deaths. Others could be seen attempting to escape by climbing down ropes.

Carlton Towers has, as tenants, several small computer software companies. That led to a high-tech twist to the drama with some of those trapped in the building alerting the world to their plight via the Twitter social networking service and also posting real-time photographs to the Internet snapped with their mobile phones.   

Survivors, most suffering from smoke inhalation, were taken to Manipal Hospital where Dr. H. Sudarshan Ballal told reporters some of the injured were put into the intensive care unit while others were quickly treated in the casualty ward.  

"Our entire hospital, medical, nursing, paramedical team, blood banks and everyone has been activated," Ballal said. "And fortunately we were able to take care of the injured in a very, very rapid fashion."  

The Hindu newspaper quotes one member of the fire department's rescue team as saying he found exit doors on every floor locked, preventing those inside the building from using the stairs to flee.

Authorities in the state of Karnataka say they will investigate to determine whether there were any violations of building or safety codes.