Two planes collided in flight in Alaska’s Mat-Su Valley, southwest of Wasilla, with two people injured, the Alaska Dispatch News reported on Saturday.

A Piper Pa-18, a two-seat single engine plane collided with an unidentified aircraft 1 p.m., local time, the Federal Aviation Administration said.

Paramedics reportedly responded to two crash sites, with one person taken to a local hospital. A second crew is working to pull another person out of the wreckage. And the person is expected to be airlifted to a local hospital.

While three National Transportation Safety Board investigators have been assigned to the case, the cause of the crash is currently unknown.

In 2011, two planes collided about 70 miles north of Wasilla in Talkeetna, leaving a family of four dead. NTSB investigators found the pilots were operating on two different radio frequencies and unable to communicate with each other, according to KTUU, Anchorage, reported.