A Los Angeles County sheriff's helicopter was struck by two bullets but managed to land safely and seven men were later held for questioning about the attack, authorities said Thursday.

The chopper was hovering over a neighborhood in an unincorporated area west of Carson when it was fired upon at about 11 p.m. Wednesday, sheriff's officials said.

The pilot heard a "thump" and decided to land at the Carson sheriff's station, Deputy Oscar Butao said.

Two bullets, apparently fired from a high-powered rifle, struck the helicopter's underside and tail, he said.

The attack was being investigated as a gang-related attempted murder of a police officer, Butao said.

"We believe this is not an isolated case," he said. "The people responsible for this are intent on killing our officers."

The pilot was not injured and an inspection determined that the craft was fit to fly, Sgt. Carol Rogers said.

An investigation led sheriff's deputies to a local home. Two nearby homes were evacuated as a SWAT team surrounded the house around 3 a.m., authorities said.

At about 3:30 a.m., the SWAT team used a vehicle-mounted battering ram to break into a garage, Butao said.

Eventually, seven men were brought out, he said. They were handcuffed and taken away for questioning but were not immediately arrested. No weapon was found.

Before it was hit the helicopter was searching for suspects in a robbery that took place nearby, but those taken into custody were not suspected of the robbery, Butao said.

Butao said it was the first such attack on a sheriff's helicopter that he had seen in his 13-year career.