Police have arrested a transient who allegedly called in a false bomb threat Wednesday afternoon in San Mateo, a police spokeswoman said.

Ahmed Siam, 48, allegedly called police dispatchers at about noon and said he had a pipe bomb and he was at 2600 S. El Camino Real, Sgt. Amanda Von Glahn said.

When officers arrived they allegedly found Siam with a metal pipe in his hand.

Siam followed the instructions of officers to put the pipe down and he was safely detained. Siam was taken to a hospital for a mental health evaluation and then to the county jail on suspicion of falsely reporting an emergency, Von Glahn said.

Police said Siam has a history of mental illness and of allegedly making false threats.

The San Mateo County sheriff’s bomb squad responded and determined the pipe was not a bomb.

Police had asked motorists and others to avoid the area until police and the bomb squad finished their work, which was at about 1:15 p.m.