A postal worker was robbed at gunpoint and locked up inside his delivery truck in Northwest D.C. Thursday evening, police said.

The worker was loading his postal truck after leaving the T Street Post Office at 1915 14th Street, near Wallach, around 6:30 p.m. when he was approached by an armed robber.

The robber took mail and an undisclosed amount of money from the truck, then locked the worker in the back of the truck, police said.

The postal worker called for help using his cellphone.

Police have not released a description of the gunman.