VANCOUVER -- Three Metro Vancouver seniors who went missing during this week's cold snap have been found, but there are two others who remain unaccounted for in the region.

And with temperatures forecast to reach -4 C overnight, the ongoing search efforts are growing increasingly desperate.

Tjeerd "Ted" Vanderveen

In Maple Ridge, a massive search effort resumed Friday for Tjeerd Vanderveen, a 72-year-old man with dementia who disappeared after heading out for a walk on Ferguson Trail the previous morning.

Authorities said Vanderveen was wearing winter clothes, but he was not prepared for a night outdoors in below-zero temperatures.

"We are very concerned," Sgt. Amanda Harnett of Ridge Meadows RCMP told CTV News.

"We have gone over many different parks yesterday and we will going back to those areas today to make sure no stone is left unturned."

Dozens of people, including search and rescue crews and police officers, are working to find the senior, and a helicopter has been deployed to assist their efforts.

While Vanderveen's family said he's familiar with the area, crews said the terrain is a concern.

"There are some steep areas that we are searching," said Rick Laing with Ridge Meadows Search and Rescue. "There are certainly some water courses and those are probably the big hazards we are looking at right now."

Vanderveen is described as white with a slim build and short grey hair. He was wearing a turquoise coat, jeans, black boots, a black toque and black gloves. The RCMP said he responds to the name "Ted."

Feng Qin Zhou

Meanwhile, authorities are still trying to find any sign of Feng Qin Zhou, a 75-year-old Richmond resident who has been missing for over a week.

She was last seen near Firbridge Way and Minoru Boulevard at around 1 p.m. on Nov. 20, and was reported missing by her daughter later that day.

Mounties said numerous resources have been involved in the search for Zhou, including the Lower Mainland Tactical Troop, the Lower Mainland Police Dog Services, the Lower Mainland Emergency Response Team and Air Services. The Canadian Coast Guard, Surrey Search and Rescue, Richmond Fire-Rescue and the Richmond block watch have also been involved in the search.

But despite receiving numerous tips from the public, police have not been able to locate her.

Other seniors found

Fortunately, there has been good news for some families in Metro Vancouver.

Seaton Faria, an 87-year-old man who disappeared on Vancouver's west side Thursday night, has been found safe, as have Surrey seniors Arpad "R.P." Sator and Robert "Bob" Pontin.

Anyone who spots Vanderveen or Zhou is asked to call 911 immediately.