ROME (Reuters) - One person was trapped under rubble and five others injured on Tuesday when an explosion, believed caused by a faulty gas canister, ripped through a street in Rome's historic centre, police said. A Reuters correspondent at the scene said a man, who had been caught in his home under fallen masonry, had not yet been rescued. An ambulance was still at the scene. Police had said two people were in a serious condition after being buried by rubble in their homes when the blast ripped through the building near Rome's Piazza Navona. A middle-aged woman trapped when her ceiling caved in was also seriously injured. She was taken away by ambulance. Police officers had earlier emerged from the second floor of a building shouting "ambulance, ambulance, there are more injured". They said earlier two passers-by were slightly hurt in the blast and two neighbours suffered scratches and shock. The building partly collapsed after the explosion. Windows were blown out of a building opposite and several cars parked in the Via dell'Orso were also damaged. Rescuers said the explosion may have been caused by a gas cylinder attached to a cooker. The street runs between the Tiber River and the Piazza Navona, which boasts the famous 17th-century Four-Rivers fountain built by Gian Lorenzo Bernini.