SAO PAULO, Brazil - A rocketundergoing final pre-launch tests exploded on its launch pad Friday, killing anunknown number of people, officials said.

"There are dead,military and civilians, but we don't know how many," said Brazilian AirForce Col. Romeo Brasileiro.

The explosion destroyed theVLS-3 rocket, which was undergoing tests at the Alcantara Launch Center nearSao Luis, 1,460 miles north of Sao Paulo.

The $2.2 million rocket wasscheduled to be sent into space next week carrying a research satellitedeveloped by Brazil's National Space Research Institute. The satellite was alsodestroyed.

The Brazilian Air Force saidin a statement there was no damage outside the launching area.

It was Brazil's third failedattempt to send a Satellite Launch Vehicle into space with a researchsatellite.

A rocket launched inNovember 1997 crashed in the Atlantic Ocean after suffering engine problemsshortly after blast-off.

In December 1999, anotherBrazilian rocket developed problems and failed three minutes after takeoff.Officials remotely destroyed the rocket.