Bastrop, Texas (CNN) -- An elite search team joined local officials Wednesday in Bastrop County, Texas, to help look for people who may be trapped in a huge wildfire that has destroyed hundreds of homes.

The cause of the Bastrop County fire, one of many burning in Texas, remains under investigation. County Judge Ronnie McDonald said during an afternoon news conference Wednesday that 576 homes had been destroyed in the county and "that number will increase."

In Leander, Texas, about 60 miles northwest of Bastrop, authorities said a smaller fire this week was believed to be the result of arson.

Investigators were searching for four teen suspects -- two boys and two girls, all believed to be 15 to 16 years old -- who were spotted running from the wooded area prior to and during the fire on Monday, the Leander Police Department said.

That fire destroyed 11 homes in the Mason Creek North subdivision. Authorities estimate the damage at $1.4 million, said Connie Watson, spokeswoman for Williamson County.

For nearly 300 days, wildfires have been taking a toll on drought-stricken Texas, scorching communities and creating dangerous conditions.

A new wildfire broke out in the western part of Camp Bullis, north of San Antonio, Wednesday afternoon, but authorities say it is already half-contained. At least 125 acres have been burned in the area and 100 homes within a quarter-mile radius have been evacuated, according to Bexar County Fire Marshall Public Information Officer Laura Jesse. Officials have called in air support to drop water and fire retardant and there is a strike team ahead of the blaze creating fire breaks, Jesse said.

An air quality alert was in place Wednesday for San Antonio, Austin, Victoria, Houston and Galveston, said CNN meteorologist Dave Hennen.

While winds were relatively calm, humidity was low, expected to be in the "very dry 10% to 20% range this afternoon," said HLN meteorologist Bob Van Dillen. "That's the real danger today."

Of biggest concern is the Bastrop County Complex fire, which has killed at least two people. It was 30% contained Wednesday.

Authorities were hoping to having the blaze contained by the end of the day Wednesday, said Mike Fischer, the county's emergency management coordinator. "We can say we're comfortable the fire won't get any larger," he said.

The fire, near Austin, began Sunday and has spread across 33,000 acres, forcing the evacuations of at least 5,000 people, officials said.

"Last night was the first night we've had (since the blaze started) with no structures destroyed," McDonald said at the afternoon news conference.

He identified one of the Bastrop County victims as 48-year-old Michael Troy Farr, a worker in the city of Austin's electrical department. Farr's body was found at his residence, McDonald said. The identity of the second victim was not released.

Authorities called on residents to take evacuation orders seriously.

"I cannot emphasize enough to Texans in the impacted areas the importance of heeding all warnings from local officials, especially evacuation orders, as these fires are mean, swift and highly dangerous," Gov. Rick Perry said.

The 600-member Texas Task Force 1 will assist local officials and first responders, Perry said.

A leadership team from the task force arrived Tuesday. "Based on the needs of local officials, a wide area search team consisting of approximately 100 members and nearly one dozen search canines will be in Bastrop Wednesday morning to work with the local incident management team and assist with search operations," Perry's office said in a statement.

The announcement did not say that anyone was missing, but said Perry made the decision to send in the team after being "briefed on the potential loss of life."

A White House statement Wednesday said Perry got a call from President Barack Obama to "express his concern for citizens of Texas impacted by the unprecedented fires." The president assured the governor "that requests for additional assistance, including as recovery begins, would be quickly assessed," the statement said.

At the local convention center in Bastrop, evacuees were stopping by to pick up supplies and water.

"It's shocking, mostly, not knowing what the end result is going to be," Bill Ludwig said.

Linda Arebalos said that while her house can be replaced, "all the memories is what really hurts, hits the heart." She said she thought about the baby pictures, the things her children made in elementary school, "the things I put up to save to give to their kids. And it's gone. It hurts."

Jerry Hooten found little more than ashes when he returned to his home and the burned-out shells of cars he had to leave behind.

"We ain't happy about it, but we're all alive," said Hooten, who is staying at an RV park outside the danger zone.

"I don't think it's registered in our brains that our house is gone and that, really, half of Bastrop is gone," said evacuee Claire Johnson.

The two people killed by the blaze were not public safety personnel, according to incident command officials, who declined to offer details.

The deaths raise the overall toll from the outbreak of fires to four lives lost. A wildfire killed a woman and her 18-month-old child Sunday when flames engulfed their home near Gladewater, officials said.

The Union Chapel fire, 18 miles from the Bastrop fire, appeared to be under control Wednesday, Fischer said.

The danger from a fire near Houston -- called the Magnolia fire -- appeared to be lessening for the most populated areas. Officials in Harris County, which includes Houston, said the fire was no longer a threat there. Also, many residents were allowed back into their homes Tuesday in neighboring Montgomery County.

About 4,000 homes in Montgomery had been evacuated, according to Lt. Dan Norris of the county's emergency management office. Firefighters continued to battle hot spots in Montgomery, but the bulk of the problems from the Magnolia fire appeared to be centered in Waller and Grimes counties, Norris said.

So far in 2011, 7.2 million acres of grass, scrub and forest have burned in wildfires nationwide. Of those, some 3.5 million acres -- nearly half -- have been in Texas, according to Inciweb, a fire-tracking website maintained by state and federal agencies.

More than 2,000 firefighters are working fires across the state, said Tom Boggus, director of the Texas Forest Service.

The drought in Texas has cost the state an estimated $5 billion this year in loss of crops and livestock, said CNN meteorologist Chad Myers. "Now fires are adding to that number."

CNN's Nicole Saidi, Jim Spellman, Josh Levs and Ed Payne contributed to this report.