County investigators identified the four as Mark Sturgis, 22, of Pennsburg; Tom Meo, 21, of Plumstead; Dean Finocchiaro, 18, of Middletown; and Jimi Tar Patrick, late teens, of Newtown Township. Sturgis, Meo and Finocchiaro were last seen on Friday.
"At this point, I just ask for your patience and your prayers for these four young men", Weintraub said.
Matthew Weintraub, the Bucks County District Attorney, on Monday called the search an "all hands on deck" situation as local and state police and the Federal Bureau of Investigation look at "all possible leads". Likewise, the vehicle of one of the men has since turned up, but there was no evidence found at the scene.
Authorities in Bucks County, Pennsylvania - about an hour outside of Philadelphia - are leading a search for four young men in their late teens to early twenties who mysteriously disappeared within about a four day time span last week. VIDEO: Search continues for 4 missing menChopper 6 was over the scene on Monday where a number of police vehicles and a mobile command center could be seen.
Investigators said the men are possibly friends, but it is unclear if there is any other connection between them. One of those locations is a wooded area on Upper Mountain Road near Route 202 in Solebury Township.
"I don't know how this is going to end up, unfortunately, but I am confident that we are going to get to the bottom of this", Weintraub said. He has also had no contact with his family or friends, and he has not shown up for work, behavior not considered typical for him.
Patrick has not been seen or heard from since 6 p.m. Wednesday, Newtown police said.
Weintraub also said he could not speak to media reports that Sturgis' auto had been found at nearby Peddler's Village in Lahaska.
When asked if he felt the four were okay, the DA said, "I can not say". Another vehicle connected to one of the men was also located in that area, the newspaper said. The case is being treated as a criminal investigation until authorities know differently, Weintraub said.
Sturgis was last seen leaving his home on Walt Road in Pennsburg, Pennsylvania, around 6 p.m. Friday to visit his friend, Meo, in Doylestown, Sturgis' father told NBC10. Law enforcement officials described Finocchiaro as standing about five-foot, nine-inches tall while weighing about 150 lbs., with brown hair and hazel eyes.
Patrick stands 5-foot-10-inches tall and weighs around 150 pounds. This story will be updated as more information becomes available.