A Mexican national – reported to be an illegal immigrant – wanted for the Texas shooting of five neighbors including a young boy, remained at large Monday morning. 

More than 48 hours after the massacre in Cleveland, Texas, outside Houston, authorities are offering an $80,000 reward for information that leads to the capture of Francisco Oropesa. 

Neighbors had allegedly asked Oropesa to stop firing his rifle in his yard late Friday so that a baby could sleep. The 38-year-old suspect, who authorities identified from video at the scene and by a Mexican consulate card, then entered the neighboring home and opened fire on five of the 10 people inside, allegedly killing the victims execution-style. 

FBI Houston, which has taken over updates from the San Jacinto County Sheriff's Office, said Sunday evening that more than 250 law enforcement officers from over a dozen agencies were actively searching for Oropesa. 

TEXAS FUGITIVE ACCUSED OF KILLING 5 WAS ILLEGALLY IN US; DEPORTED 5 TIMES

"FBI Houston and other local, state, & federal agencies will not stop assisting SJSO until he is captured and justice is brought on behalf of the five victims," they said.

FBI Special Agent in Charge James Smith announced Sunday an additional $25,000 FBI reward in connection with the investigation. 

That increased the total reward amount to $80,000, up from the combined $55,000 being offered by Texas Gov. Greg Abbott's office and multi-county crime stoppers. 

"My heart is with this 8-year-old little boy. I don't care if he was here legally. I don't care if he was here illegally. He was in my county. Five people died in my county. And that is where my heart is. In my county, protecting my people to the best of our ability," San Jacinto County Sheriff Greg Capers told reporters in an update Sunday afternoon.

Capers said that he was supposed to escort the widow of a constable who died about a year ago to a Texas police officers' memorial Sunday night but explained to her why he could not. 

"My main intent and focus is 100% on capturing this suspect," Capers said. The sheriff also said he would not be at the vigil for the slain boy held at Northside Elementary in Cleveland. "Once again, I would love to be there, but I'm going to be here looking, searching for the suspect," Capers added. 

Anyone with information that could lead to the arrest of Oropesa is asked to call 1-800-CALL-FBI with tips. 

MEXICAN NATIONAL WANTED IN DEADLY TEXAS SHOOTING OF 5 NEIGHBORS ‘COULD BE ANYWHERE,’ SHERIFF SAYS 

"We're asking everyone for your help so we can bring this suspect – or this monster, I will call him – to justice," Smith said at the same press conference Sunday. "Right now we just don't know because if we did we would have him in custody. We do not know where he is. We do not have any tips right now where he may be." 

"I can pretty much guarantee you, he's contacted some of his friends. We just don't know which friends they are," Smith added. "That's what we need from the public, any type of information, because right now we're just – we're running into dead ends." 

Capers told reporters that two women were found lying on top of and trying to protect three surviving children inside the home Friday night. The three children were loaded into an ambulance and brought to a hospital, where it was discovered they had not been physically injured. Four adults were found deceased at the scene: Sonia Argentina Guzman, 25; Diana Velazquez Alvarado, 21; Julisa Molina Rivera, 31; and Jose Jonathan Casarez, 18. Daniel Enrique Laso Guzman, age 8 or 9, was airlifted to a hospital, where he was declared deceased. 

Another survivor, Wilson Garcia, whose wife Sonia and third-grade son were murdered, spoke to reporters at a vigil hosted Sunday afternoon at the school the boy had attended. 

"My wife died, and my 9-year-old son died," Garcia said in Spanish. "What can I say, I am trying to stay strong for my children. My daughter kind of gets, understands things. It's hard when she comes to me and starts asking for her mom and her brother."

Garcia said another woman in the house told him to save himself. 

"She told me to throw myself out of a window because my children were already without a mother," he said. 

The deceased victims are said to have been from Honduras, according to local reports. 

A source with U.S. Immigration and Customs Enforcement (ICE) told Fox News that Oropesa has been previously deported, has "multiple" illegal re-entries on his record, and was last encountered by ICE in 2016. A second source, within the Department of Homeland Security, told Fox News that Oropesa had been deported five times between 2009-2016. 

Fox News's Bill Melugin contributed to this report.