A Texas man set his house on fire, then stole a small plane and crashed it into a building containing a federal tax office Thursday, CNN reported citing federal officials.
"This was apparently - according to an official - a deliberate act," CNN anchor Tony Harris said. "Joseph Andrew Stack is the name of the pilot."
The plane struck the second floor of the four story building in Austin, Texas about 10 am (1600 GMT) and burst into flames in a massive explosion Thursday that forced people to flee out of the windows, witnesses and officials said.
There was "no known link to terrorism" the Department of Homeland Security said, noting that the cause of the crash was not yet known.
However, North American Aerospace Defense Command launched two F-16 fighter aircraft from Ellington Field in Houston today to conduct an air patrol in response to the crash.
"This response from NORAD is a prudent precaution and consistent with our response to recent similar air incidents," Jamie Graybeal, spokesperson for NORAD, said in a statement. Two people were taken to hospital and one person was unaccounted for but fire officials said they believed everyone else had been safely evacuated from the building.
"The building shook, it's almost like an earthquake," a witness named Cynthia who was in a neighboring building in the complex told CNN.
Cynthia and her office mates left the building and saw people running towards the building that got hit by the plane.
"People were on the second floor. They couldn't get out. They were hanging out the windows screaming for help."
Fire officials were battling to contain the blaze.
"What they're seeing is heavy fire around the second floor. They've got lots of smoke. Lots of heat. Lots of fire," assistant fire chief Harry Evans, assistant fire chief told reporters.