Two Fort Worth SWAT officers were injured Tuesday night when a flash bang device exploded in an officer's hand, police said.

The officers were at the police training center, where they were staging prior to serving a search warrant at another location, when the accident happened, said department spokesman Sgt. Marc Povero.

One officer was rushed to Parkland Memorial Hospital in Dallas with serious burns to his hand, Povero said.

Another officer went to John Peter Smith Hospital complaining of trouble hearing.

The SWAT officers often use stun grenades as a distraction device. Police say they don't know why this one went off unexpectedly while an officer was holding it.