Authorities were searching for a gunman after a robbery at the Comerica Bank in Downtown Long Beach Tuesday morning.

The stick-up happened just before 10 a.m. in the bank branch at Long Beach and Ocean boulevards, according to Long Beach police.

Someone triggered an alarm inside the bank, prompting officers to rush to the scene, LBPD spokesman Carlos Sandoval said.

The robber managed to evade police for the meantime, and authorities called in the FBI to investigate, which is typical procedure for bank robberies, Sandoval said.

Sandoval declined to say how much cash the robber managed to escape with, and no suspect description was immediately available.