Two men in Utah were arrested after an incendiary device was placed under a news media vehicle in Salt Lake City on Friday, according to court documents obtained by CBS News.

The device had been lit but "failed to function as designed," a Unified Fire Authority Investigations officer wrote in affidavits of probable cause filed in the 3rd District Court of Salt Lake County. Fox 13, a news station based in Salt Lake City, confirmed to CBS News that the device was placed under their vehicle, which was parked next to an occupied building.

Authorities arrested Adeeb Nasir, 58, and Adil Justice Ahmed Nasir, 31, who were booked at Salt Lake County Jail on Sunday and could face charges that include attempted aggravated arson, threat of terrorism and possession of weapons of mass destruction, according to the documents. They are being held without bail.

"Due to the nature of the device and its placement, this incident constituted a significant threat to public safety," Unified Fire Authority Investigations officer Jeffrey David Nelson said in the affidavit, noting a risk of mass casualties.

The FBI, which is leading the investigation with assistance from the Unified Fire Authority bomb squad, identified and tracked the suspects to a home on the outskirts of Salt Lake City.

At the residence, investigators located firearms, illegal narcotics and hoax weapons of mass destruction -- devices that don't contain anything harmful but appear legitimate. The suspects claimed those devices were real, prompting evacuations in neighboring residences. Both men had protective orders preventing them from legally owning firearms due to histories of illicit drug use.

It's unclear if the two suspects have obtained legal representation.

A Unified Fire Authority official told CBS News that no further information will be shared at this time, citing the ongoing investigation.

The death of conservative activist Charlie Kirk, who was shot last week at an event at Utah Valley University, about 40 miles from Salt Lake City, has drawn a higher media presence than usual to the area. Investigators are still determining a motive for the attack and charges are expected to be filed this week against the suspect, 22-year-old Tyler Robinson, according to the Utah County Attorney Jeff Gray.

2 arrested after incendiary device placed under news vehicle in Salt Lake City