An empty boat trailer came loose from a pickup and smashed into a bicyclist at around 7 p.m. Tuesday in South Anchorage, police say.

The 27-year-old cyclist, who police have not publicly identified, suffered severe injuries to his head and leg, said Lt. David Parker, a department spokesman.

The truck was headed west on O'Malley Road towing a rusty, single-axle trailer, Parker said. The trailer apparently detached from the truck near the Seward Highway overpass, struck the cyclist and lodged against a light post and sign on the north side of O'Malley, police said.

The bicyclist was headed west and never saw the trailer coming, Parker said.

The trailer did not appear to be attached to the truck with a safety chain, as is required by law, Parker said.

Police are investigating the accident and have not named the driver.