UPDATE Friday at 9:30 p.m. :
Buffalo Police have identified the missing police diver as Craig Lehner, 34, of Buffalo.
Lehner graduated from the police academy in 2008. He has been working with the K-9 unit, partnering with police dogs. He has been with the underwater search and rescue team for about a year.
Buffalo Police said the search for a missing police diver is "still a rescue," as night falls on the city.
According to investigators, the 34-year-old diver -- who's been with the department for 8 years -- was participating in a routine training exercise when he vanished around 12:50 p.m.
Crews from multiple agencies have concentrated the search at the foot of Ferry Street in Buffalo.
Coast Guard crews said as part of their search efforts, they discovered the cable keeping the diver secured against the current had broken. They initially thought they discovered the diver's secondary dive tanks on the water's surface, but police said what was found was actually a spare tank that came off an unrelated boat.
The Coast Guard is now on-site, along with Grand Island Fire and Buffalo Police. Other agencies were called in to assist, including a crew from Coast Guard Air Station Detroit, aboard an MH-65 Dolphin helicopter.
Buffalo Mayor Byron Brown visited crews at Unity Park as they searched Friday. Some local elected officials have weighed in on the search efforts on Twitter.
— Erie County DA (@da_erie) October 13, 2017
Prayers for the diver, his family, and everyone searching and attempting to rescue.
— Joseph Lorigo (@JosephLorigo) October 13, 2017
I am praying for the @BPDAlerts Officer we want to find them safe
— EC Sheriff Howard (@ECSheriffHoward) October 13, 2017
This is a developing news story. We'll continue to keep you updated as more information becomes available.