Police are investigating after two people walking on the Golden Gate Bridge near San Francisco were hit with blow darts.

A man who had been hit in the leg by a 5-inch long dart flagged down a California Highway Patrol officer on bicycle, according to a Los Angeles Times report.

A woman came upon the scene when more emergency personnel arrived and said she had also been hit by a blow dart in the knee. Both were released at the scene after being treated.

Authorities think the darts were fired from a blow gun. It was likely fired from a moving car based on where the darts struck the victims. Both had been walking southbound on the east sidewalk at the time.

Police have taken both darts and are testing them to make sure there are no chemicals or toxins on them. They will also be reviewing video footage to see if the assailant can be spotted.

Blow guns are simple weapons usually consisting of a tube for firing darts. Usually, an individual inserts a projectile into the weapon and then blows on it, expelling the dart.

Blow guns are often used in competitions around the world, and there has been an effort to get it included in the Olympics.

Blow guns have been used in many cultures, but they are most commonly associated with Southeast Asia, the Amazon region of South America, and Guatemala in Central America.