A small fire erupted and two sailors were injured after an aerial target drone malfunctioned and struck a guided missile cruiser during training off Southern California on Saturday.
The drone struck the USS Chancellorsville on the side, leaving a 2- to 3-foot hole, said Lt. Lenaya Rotklein of the U.S. Third Fleet.
"They're trying to figure out what happened," she said, adding, "It's certainly rare."
The accident happened Saturday afternoon while the ship was testing its combat weapons system off Point Mugu. The drone was being used to test the ship's radar, Rotklein said.
The two sailors are being treated for minor burns, Rotklein said. The ship was heading back to Naval Base San Diego so officials can assess the damage.
The Navy was investigating the cause of the drone malfunction.
An estimated 300 sailors were aboard the missile cruiser at the time of the incident.
This is the second military drone crash in a week. On Tuesday, a drone from Fort Drum in upstate New York crashed into Lake Ontario during a training flight. The Air Force is investigating that incident.
NBC's Courtney Kube and the Associated Press contributed to this report.