Updated

Residents returned to their homes along the Rio Grande (search) on Thursday as firefighters tried to stamp out the remnants of a smoldering blaze that transformed a riverside forest into a patchwork of black and gray.

The suspected arson fire began Wednesday night and scorched about 165 acres. About 200 people were forced to abandon their homes and spent the night in hotels or the homes of friends and relatives.

Marlene Roberts fled her home with her husband, David, after he placed garden sprinklers on the roof.

"We could see these huge flames, and then you'd see just huge fireballs and these loud explosions. It was so eerie, both fascinating and terrifying at the same time," she said.

About 200 firefighters were on the scene Thursday as two National Guard (search) helicopters dumped massive buckets of water on remnants of the blaze. Crews also quelled a flare-up during the afternoon.

The fire was the second in the Rio Grande area in as many days. The first, just to the south of the second, burned about 350 acres after it was started Tuesday. It was 75 percent contained Thursday, fire officials said.

Investigators were looking for two juveniles who might have set off fireworks that sparked the first fire, and for an adult who may have been responsible for the second blaze, said Mayor Martin Chavez (search).

Gov. Bill Richardson on Thursday ordered a 19-mile stretch of the heavily wooded Rio Grande region closed through July 4.

The forested area -- popular with bicyclists, joggers, walkers, birders and nature lovers -- is laced with trails and features a paved path for cyclists and inline skaters.

The New Mexico National Guard deployed 120 soldiers and airmen to help ensure the safety of the public, said Brig. Gen. Kenny Montoya, the Guard's commanding officer.

Meanwhile, firefighters outside Tucson, Ariz., got help from the weather for a second day Thursday as they made progress on containing a wildfire that devastated a mountaintop community.

Calmer wind and higher humidity made it easier on crews building and strengthening firebreaks around the blaze, which burned about 345 buildings in and around Summerhaven on Mount Lemmon.

The fire began June 17 on the 9,157-foot peak northeast of Tucson. Driven by wind, flames roared through Summerhaven on the southern side of the mountain on June 19 and continued burning across the top of Mount Lemmon and down the north side.

The blaze has charred more than 30,000 acres, much of it pine forest, but is now 35 percent contained. The cause remains under investigation.