Law enforcement officials took to horseback on Sunday in the search for 46-year-old Gonzalo Lopez, a convicted murderer who escaped from a prison transport bus on Thursday after stabbing the driver and fleeing on foot.
Lopez escaped in Leon County, a rural area in between Dallas and Houston that has about 16,000 residents.
"We have no reason to believe he has left the area," the Leon County Sheriff's Office said Saturday. "There is no evidence to support that, at this time."
Lopez is serving a life sentence for kidnapping a man and killing him with a pickax in Hidalgo County near the U.S.-Mexico border in 2006, as well as attempted murder for shooting a police officer in Webb County a couple of years earlier, according to Fox 4 Dallas.
He overpowered and stabbed the driver before the transport bus crashed on Thursday, authorities said. The driver, a corrections officer, sustained non-life-threatening injuries.
The Leon County Sheriff's Office, Texas Department of Criminal Justice, Texas Department of Public Safety, and other agencies were involved in the search on Sunday.
Dozens of law enforcement officers were on horses and using dogs to try to locate Lopez.
A $50,000 reward is being offered for information leading to Lopez's capture.
Authorities have warned residents not to approach the fugitive if they see him.
"If you live in the search area, be extremely cautious and keep all doors locked on houses, buildings, and vehicles," the Leon County Sheriff's Office said.
The Associated Press contributed to this report.