Department of Transportation technicians are trying to determine whether lightning may have struck at the Harano Tunnels causing sensors that determine whether vehicles are too tall to enter the tunnels to automatically go off. 

DOT spokesman Tim Sakahara said operators at the H-3 operation center, manned 24/7, reported hearing loud thunder at 1:36 p.m. Friday at the time the sensors went off, and that lightning may have struck. 

Red lights stopped both lanes of traffic into the tunnel, causing traffic to stop momentarily, Sakahara said. 

Operators checked and found no vehicle exceeding height limits, and manually turned the signals off, allowing traffic to flow again. 

Technicians are trying to determine what caused the sensors to go off.