EAST LONGMEADOW – Two police officers, training on patrol rifles at the Smith & Wesson shooting range in Springfield, suffered injuries Wednesday morning when one of the firearms exploded.

“For one reason or another the weapon had a failure, we really haven’t determined the cause yet,” said Sgt. Patrick Manley. “A round exploded in the chamber and caused the weapon to blow to pieces...It just blew up.”

Officer Daniel Atwater, who had been firing the rifle, suffered burns and trauma to his left hand, The three-year veteran could be out for some time while he recuperates, Manley said.

Officer Edward Rice, a 20-year-veteran was struck in the shoulder by a piece of the exploding firearm and suffered a minor laceration. He may be out for a short time as well, Manley said.

Both officers are expected to fully recover, Manley said, adding that both Smith & Wesson and East Longmeadow police are attempting to determine what caused the rife to explode.

“Smith & Wesson’s interest in this is probably as keen as ours,” Manley said, adding that the firearm pieces are currently being held by the company for testing.

Paul Pluff, director of marketing and customer service at Smith & Wesson, said an initial on-site inspection of the firearm indicated that the explosion was not due to a defect in it.

Such malfunctions are extremely rare Pluff said. “Right now this is a stand-alone incident.”

Smith & Wesson engineers and metallurgists continue to probe the malfunction. “There is a number of things that can cause this to happen,” Pluff said.

Manley said Atwater’s injuries were consistent with someone who had had a firework go off in his hand. “Luckily, the energy was dissipated forward to his hand and not towards his face,” he said.

The weapon in question is an M&P 15, Manley said, adding that the department has had them since 2008. The department has taken its rifles out of service while it probes the malfunction.

Manley said the department had been on its third day of training at Smith & Wesson and the rifle in question had been used in prior training sessions. The rifle had probably been fired some 80 to 100 times that morning when “all of a sudden - boom - it didn’t work properly,” he said.

The explosion caused the rifle to break into two large pieces and several smaller pieces, Manley said, adding that both officers had been standing at the time.

The M&P 15 is widely used by law enforcement agencies and is known for its reliability, Pluff said. “They are all across the country.”