PLEASANTON, Calif. (KRON) — Authorities on Tuesday announced they are scaling back the search for missing runner Philip Kreycik, who was last seen Saturday near Pleasanton Ridge Regional Park.

“This was not an easy decision to make, and our focus is to continue supporting the Kreycik family,” said Lieutenant Erik Silacci, “We thank all of the search and rescue crews as well as the hundreds of volunteers who rallied together and remain committed to locating Philip.”

Authorities said no significant clues were collected during the search efforts and it is believed that Kreycik is either incapacitated or not in the general area.

This remains a missing person investigation, officials said.

Hundreds of people, including state and local authorities plus volunteers, joined the fourth day of searching for Kreycik.

Kreycik, 37, went for a run in the area of Pleasanton Ridge Regional Park on Saturday afternoon and never came back. His wife reported him missing.

Authorities said they found his phone and wallet inside his car, parked by the Moller Ranch trailhead.

On Monday, authorities moved the command center to Foothill High School so search crews can enter the hills in Pleasanton from a better vantage point. Police also began using airplanes equipped with infrared technology to detect Kreycik from above.

The father of two is in good health and is a part of a running club, police have said.

In a press conference later Tuesday, Alameda County officials discussed the latest on search efforts for Kreycik.

You can watch the press conference below:

Nearly 300 people have been searching for Kreycik since he went missing.

By Tuesday night, crews will have about 85% of the region searched via foot, drones, and in the air.

Authorities believe they know the intended route Kreycik was going to run – about 8 miles – and that it is possible to slip off a ridge in the area, but that would not have been likely on his intended route.

“We’re left with basically two probabilities. One is that we’re not finding Philip here in the terrain and that he’s incapacitated. Or he’s not here.”