CNN
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Weeks of unexplained drone sightings in New Jersey have left residents, politicians and public safety officials confused, raising safety concerns.

While New Jersey Gov. Phil Murphy has stressed that there is no known threat to public safety, residents and several officials are calling for a response to the drone activity as experts work to figure out exactly what is going on.

When and where were the drones spotted?

According to the Federal Aviation Administration, the sightings began on November 18 near Morris County, New Jersey. Some people have described the drones as being as big as bicycles or small cars.

“We have reports from the public and law enforcement dating back several weeks,” the FBI Newark field office said Dec. 3.

New Jersey residents have described seeing the drones flying overhead, sometimes in groups. Drone sightings have been reported in Morris and Somerset counties, according to local officials. Both counties are in the New York metropolitan area.

However, the sightings were not just among concerned residents. The U.S. Coast Guard, part of the Department of Homeland Security, said one of its employees came across the drones.

“Several low-flying aircraft were observed near one of our vessels near Island Beach State Park,” said Lt. Luke Pinneo of the Coast Guard told The Associated Press on Wednesday.

The planes were not considered an immediate threat and did not affect operations, Pinneo added. CNN has reached out to the Coast Guard but did not receive an immediate response.

After drones were spotted near Picatinny Arsenal, a U.S. military research facility in Wharton, and over President-elect Donald Trump’s golf course in Bedminster, The FAA issued temporary flight restrictions for the properties.

Travel content writer Katie Caf, 29, said she spotted five potential drones the size of bicycles moving in a “zigzag pattern” on Saturday.

West Milford Mayor Michele Dale reported 60 drones flying over local reservoirs.

Federal authorities have ruled out any connection by local, state or federal governments to the sightings.

“From what we know, we are not aware of any risks to public safety,” Murphy told CNN affiliate WBGO on Wednesday.

“Is it frustrating not having answers? Is it frustrating not to do it? Do you have a source for these things? Yes,” the governor told the radio station.

The drones operate primarily at night and often display flashing lights, but they turn off the lights and avoid police helicopters when they approach, Mayor Michael Melham of Belleville Township said in a Facebook video update Wednesday.

It’s possible the drones could evade radar detection because they don’t emit frequencies or have evasion capabilities, Melham suggested.

Pentagon officials quickly refuted claims by U.S. Rep. Jeff Van Drew, a New Jersey Republican, that the drones came from an Iranian “mother ship” off the U.S. East Coast.

“There is no truth to that,” said Pentagon deputy press secretary Sabrina Singh. “There is no Iranian ship off the coast of the United States and there is no so-called mother ship launching drones toward the United States.”

Local officials from Morris and Somerset counties in New Jersey acknowledged the “recurring reports of drone activity” and public concerns in a joint news release Thursday.

Officials have directed the public to share tips, sightings and videos of possible drone sightings.

“The FBI-Newark and NJ State Police are urging the public to report any information related to recent sightings of possible drones. Anyone with relevant information is asked to call the FBI at 1-800-CALL-FBI (1-800-225-5324) or submit it online at Tips.fbi.gov. Citizens can also upload videos via the latter website,” the statement said.

This is a developing story and will be updated.