Update: Officials say human remains have been found as they search for the four missing men on Friday according to KJRH.

It is not known if those remains are those of the missing men.

OKMULGEE, Okla. (KFOR) – Investigators in Okmulgee are searching for four men who haven’t been seen or heard from in nearly a week.

Police say family members of 32-year-old Mark Chastain, 30-year-old Billy Chastain, 32-year-old Mike Sparks, and 29-year-old Alex Stevens reported them missing on Monday.

The Okmulgee Police Department says all four are close friends and are believed to have left Billy Chastain’s house on the west side of Okmulgee on Sunday night.

All were reportedly on bicycles.

Officials say they have received several reports of potential sightings of the men, but say they have been unable to confirm any of the sightings.

“Mark Chastain’s phone was tracked to an area south of Okmulgee but was turned off or lost power. Officers have checked that area and found no sign of any of the men. Although there is no evidence to indicate violence or any foul play at this point, a small contingent from District 25 Violent Crime Task Force is assisting which allows us to bring more resources to bear in the search,” the police department posted on Facebook.

Authorities say they have been scouring surveillance footage but they aren’t having much luck finding a path the men may have taken.

“It is important to remember that without an actual appearance of the missing men on video along the path we have been able to establish by phone data, we can’t definitively say the missing men took that path. Rather only one of their phones did. We will continue to investigate and are following any evidence we uncover,” the department posted.