LONDON, FEB. 16 (TUESDAY) -- A car exploded in flames and killed its driver early today at the entrance to Downing Street where Prime Minister Margaret Thatcher lives, police said.

The cause was not known.

A spokesman for the prime minister said Thatcher was at her residence at No 10 Downing St. at the time of the explosion but was not harmed.

The explosion, shortly after 1 a.m (8 p.m. EST Monday) was seen by a police officer on duty at metal security barriers at the entrance to Downing Street -- a short road of government offices and official residences that runs off Whitehall.

A police spokeswoman said: "It appears a car pulled up in Whitehall at the entrance to Downing Street and burst into flames.

"The fire was put out by London Fire Brigade and the body of a man was found inside the car."

The car came from the direction of the houses of Parliament. The area was sealed off as police investigated the wreckage. There was no immediate information on the identity of the dead man. Firemen said the body had been very badly burned.

Thatcher's spokesman would not speculate on the cause of the fire.

"It is a matter for the police. We are not aware of any direct connection with Downing Street," he said.