Union officials in Texas said an “ambush” was to blame for the death of a 36-year-old Border Patrol agent who was found with head injuries over the weekend. Agent Rogelio Martinez died Sunday after being found at the bottom of a 14-foot culvert late Saturday. He and his partner—who sustained serious injuries but survived—had been patrolling the Big Bend area when they were injured in circumstances that are not clear. “What we know is that Border Patrol Agent Rogelio Martinez appears to have been ambushed by a group of illegal aliens whom he was tracking,” Brandon Judd, a Border Patrol agent and head of the National Border Patrol Council union, was cited as saying by the Los Angeles Times. Judd said Martinez “was struck in the head multiple times with a rock or rocks.” The FBI has confirmed that Martinez and his partner were found at the bottom of the culvert with serious head injuries but given no further details. A separate report by the Associated Press on Monday cited a U.S. official saying Martinez’s partner has no recollection of events and investigators are looking into whether Martinez fell.