BEAVERTON, Ore. -- Police are looking for three people after a security guard was attacked Friday.

The security guard, on routine patrol, spotted two people milling about a construction site in the area, police said. The two teenagers took off running when the guard approached them, officers said.

Moments later, police said, a third person struck the guard from behind.

The security guard called for help and police arrived. They searched the area with a K-9, but never found the three people responsible.

Police said the trio may have been trying to steal tools from the construction area. The attacker and the other two people are wanted on assault and trespass charges.

The security guard was treated at the scene and didn't require a trip to the hospital.

Anyone who saw any suspicious activity around Sunset High School early Friday morning is asked to call Beaverton police.

Security Guard Attacked At Sunset High