Fires set in the riparian area along the San Juan River burned bright through the night Thursday, their red glow illuminating the blackened sky and creating perfect silhouettes of police officers patrolling on foot with rifles slung across their backs.

This next phase of the 34-day-old manhunt for two survivalists accused of killing a Colorado police officer and wounding three others accomplished just what local law enforcement hoped: It cleared out the brush, trees and grasses that some say is as "thick as dog hair" along the river and gave officers a better vantage point from which to do surveillance.Officers started a handful of fires up and down the 14 miles of river between Montezuma Creek and Bluff at 3 p.m. Thursday. A second round of fires was started around 7 p.m., San Juan County Sheriff Mike Lacy said.

The object was not to be mistaken as an attempt to burn or smoke out fugitives Alan "Monte" Pilon and Jason McVean, Lacy said emphatically.

"We're not here to burn anybody out. We're trying to cut a path through there, open up some of these places to get a better look at what's in there," Lacy said. "Now if somebody is moved out because of what we're doing, that's something else."

Officials several days ago began talking about starting the fires but were delayed because of disagreements with federal officials over the plan.

Lacy wanted to use canisters of antifreeze-filled ping-pong balls to ignite the river bottom foliage, which includes tamarack bushes, cottonwood and Russian olive trees.

But Bureau of Land Management and U.S. Forest Service officials balked, saying they wanted the FBI to assume control of the operation if that method was used.

Local officials had hoped to burn through a swath of brush about 6 miles long. Instead, only about a half-mile length of the brush is burned out, Lacy said Friday. The FBI was not asked to take control of the operation.

The ping-pong-ball method is commonly used in fire suppression. When dropped from aircraft, the canisters ignite fires on hitting the ground.

"In my opinion, I think the (federal officials) think it looks too much like an assault," Lacy said. "From a public-relations standpoint, nobody wants a Waco on the river."

The sheriff hopes officials still can reach an agreement sometime today, but the manhunt may be scaled back by Saturday if negotiations continue to flounder.

Only about 150 officers from 20 different agencies are involved in the manhunt, where once more than 400 from 51 agencies were on the job.

"This is a whole different ball game," Lacy said.

Pilon, 30, Dove Creek, Colo., and McVean, 26, Durango, Colo., have eluded police since May 29, when Cortez, Colo., police officer Dale Claxton was shot and killed during a traffic stop. That triggered the manhunt that has led police across the deserts and canyons of the Four Corners area.

On June 4, a third suspect in the Claxton shooting, Robert Mason, 26, also of Durango, fired a shot at a Utah state worker looking for a place to eat lunch near Swinging Bridge just west of Bluff, San Juan County.

He also shot and wounded San Juan County Deputy Sheriff Kelly Bradford and then turned the gun on himself. Mason was found dead not far from Swinging Bridge in a small dirt bunker wearing camouflage, a combat-style helmet and a bulletproof vest. His body was surrounded by pipe bombs, police said.

The intensive manhunt lasted six days, tapering off from roadblocks and evacuations to patrol work and following up on leads.

But all that changed Sunday when a teenage girl spotted Pilon and McVean - men she described as dressed in camouflage and carrying guns - snooping around a water truck at Lee's Trucking in Montezuma Creek.

Only about 60 officers were working the manhunt around the clock this week Lacy said.

Helicopters crisscrossed the skies above the river in the twilight Thursday, monitoring the flames and watching for the suspects.

As of Friday morning, no new sightings had been reported, Lacy said.