The Navy’s Unmanned Patrol Squadron (VUP) 19 is temporarily standing down operations while it investigates the crash of an MQ-4C Triton in California this week.

A Triton conducting operational testing out of Naval Base Ventura County in California on Wednesday “had an issue during flight and the decision was made to bring it back to base. While heading in for landing, the engine was shut down but the landing gear did not extend. The aircraft landed on its belly on the runway. No one was hurt and there was no collateral damage,” Cmdr. Dave Hecht, a spokesman for Naval Air Force Atlantic, told USNI News today.

The incident is still under investigation, with the Navy still looking into the cause of the malfunctions and the cost estimate of the damage to the aircraft. Hecht did say that the cost was expected to be more than $2 million, marking this incident as a Class A aviation mishap.

While the investigation goes on, VUP-19 – which has a dual-site command structure at both Naval Base Ventura County and Naval Air Station Jacksonville, Fla. – will cease flying for an indefinitely amount of time.

VUP-19 stood up at NAS Jacksonville in October 2016 and was the first squadron in the Navy to consist solely of unmanned aircraft. The squadron falls under Patrol and Reconnaissance Wing 11 and is collocated in Jacksonville with the wing’s P-8A Poseidons, a manned airplane that also conducts maritime surveillance. The Tritons and Poseidons were identified as a natural pairing for manned/unmanned teaming and have already proven their ability to pass information from the unmanned plane to the operators aboard the manned P-8s.

The Navy has said it would deploy its first operational Tritons to Guam by the end of this year, and the unmanned aircraft in California were conducting tests ahead of that deployment to Guam.