(AP) — Three people were killed after two small planes collided in Northern California while trying to land at a rural airport, authorities said Friday.

The names of those killed after their planes crashed Thursday at the Watsonville Municipal Airport will be released once their families have been notified, the Santa Cruz County Sheriff’s Office said in a statement.

There were two people aboard a twin-engine Cessna 340 and only the pilot aboard a single-engine Cessna 152 during the crash, according to the Federal Aviation Administration.

The city-owned airport does not have a control tower to direct aircraft landing and taking off. The airport accounts for about 40% of all general aviation activities in the Monterey Bay area, according to the City of Watsonville’s website.

Watsonville, an agricultural town near Monterey Bay, is about 100 miles (160 kilometers) south of San Francisco.

The sheriff’s office said the Federal Aviation Administration and the National Transportation Safety Board were investigating.