BILBAO, Spain (AP) _ Investigators have ruled out sabotage in a helicopter crash that killed three Basque television journalists, an official said Tuesday.

The chopper slammed into a quarry Monday near the Basque town of Markina while the crew from Euskal Telebista, a regional public broadcasting station, was filming a nature series.

The victims were identified as producer Inaki Pangua Akasuso, cameraman Ruben Cortijo Marin and Roberto Arenas Gonzales, the pilot.

The fourth occupant, newspaper photographer Santiago Naniz Aramendia, remained in critical condition.

``The helicopter was flying low and a blade got caught on a metal cable running across the quarry,'' said Jose Olano, a Basque interior ministry spokesman.

He added that police did not suspect any foul play despite a recent letter bomb explosion that injured a journalist who had denounced the violent Basque separatist group ETA.