Police in Grapevine, Texas, conduct a news briefing concerning an inmate who escaped custody after allegedly stabbing a Miami-Dade police officer.

Texas authorities fanned out Wednesday in a manhunt for a prisoner who police say wriggled out of custody in a Walmart parking lot by snapping his eyeglasses and using the jagged edge to stab an officer guarding him.

The state quickly placed the prisoner, Alberto Morales, on its list of 10 most-wanted fugitives and offered a $10,000 reward. The state said he should be considered armed and dangerous.

“He’s made it pretty clear that he’s not going back to prison,” said Sgt. Robert Eberling, a police spokesman in the Dallas suburb of Grapevine, quoting authorities’ interviews with Morales’ former cellmates.

Morales, 41, was being flown from Miami to Nevada on Monday to serve a prison sentence for aggravated sexual assault. Two Miami detectives were flying with him, with a connection in Houston.

On the first leg of the trip, Morales acted erratically and banged his head against the seat in front of him, Miami police told NBCMiami.com. The three were not allowed to board their connecting flight to Las Vegas.

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The detectives decided to rent a car and drive the rest of the way, and were picking up a third officer in Dallas to help. The first two detectives and Morales stopped at a Walmart so one of the detectives could use the bathroom.

That is when Morales took off his glasses and broke the frame to make a blade, police said. The detective left guarding him, Jaime Pardinas, was stabbed once in the chest and three times in the back. Morales ran away. The detective was treated at a hospital.

Police in Grapevine were also looking for an SUV that Morales may have stolen from a motel overnight Monday. There was a gun in the SUV, a white 2008 Ford Explorer with a Texas license plate, police said.

Before Morales broke free, his hands were shackled to a band around his waist.

“He was handcuffed. We don’t know how he got the handcuffs free,” Miami-Dade County Police Director J.D. Patterson told NBCMiami.com.

Eberling said Grapevine police do not know whether Morales is still shackled.

Grapevine police said Morales would face four additional criminal charges because of the escape attempt, including attempted capital murder.

Police across north Texas were looking for Morales, with Miami police and U.S. marshals helping.

“We don’t think he could have gotten too far,” Grapevine police spokesman Lt. Barry Bowling told NBCDFW.com. “We’re concerned about where he might be since he’s at large, and we do think he’s still very dangerous.”

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