PRINCETON, N.J. (AP) — Dozens of drones have been spotted at night across New Jersey in recent weeks, including near sensitive sites such as a military research facility, Gov. Phil Murphy said Monday.

Murphy said the drones don’t appear to pose a public safety concern.

The FBI has been investigating reports about the mysterious nighttime drone flights that started occurring last month across central New Jersey and has asked the public for help. Since then, residents have reported seeing drones in other areas.

While speaking at an unrelated bill signing event in Princeton, Murphy noted there were 49 reports of drones on Sunday, mostly in Hunterdon County. The Democratic governor said those numbers included possible sightings and potentially the same drone being reported more than once.

“This is something we’re taking deadly seriously. I don’t blame people for being frustrated,” Murphy said.

It’s unclear who is piloting the drones and why, but federal and state officials have repeatedly stressed that there is no known threat to public safety.

Drones are legal in New Jersey for recreational and commercial use, but they are subject to local and Federal Aviation Administration regulations and flight restrictions. Drone operators also must be FAA certified. Most, but not all, of the drones spotted in New Jersey were larger than those typically used by hobbyists.

The flights initially raised questions in part because they took place near the Picatinny Arsenal, a U.S. military research and manufacturing facility, and over President-elect Donald Trump’s golf course in Bedminster.

Most of the drones have been spotted along coastal areas, and some of the devices were recently spotted over a large reservoir in Clinton.

The FBI asks that residents share any videos or photos they may have of the flights, along with any other relevant information.

U.S. Rep Chris Smith, a Republican, said he was on Long Beach Island Monday night with Ocean County Sheriff Mike Mastronardy to look into the situation.

“Understandably, New Jersey residents are very alarmed at this significant and reoccurring phenomenon, and the tepid response from our state and federal agencies so far is totally unacceptable,” he said. “The people of New Jersey deserve swift and bold action on the part of our state and federal agencies to investigate, assess, and address the situation immediately and to alleviate the growing concerns of our community.”