Thai police found on Tuesday (November 5) the getaway car used to jailbreak American 'drug dealer' Bart Allen Helmus, 39.
The vehicle was abandoned on a motorway in Si Racha district of Chonburi, some 35 miles form the scene of escape.
The three prison escapees are believed to have then changed into a second car and fled to a hideout or disappeared into neighbouring Cambodia.
Bart Allen Helmus, 39, was appearing in court in Pattaya, Thailand, yesterday (November 4) afternoon with his Thai girlfriend Sirinapha Wisetrit, 31, after they were arrested in July for allegedly supplying meth.
They faced the maximum death penalty of execution.
The pair were inside the court building with a third prisoner, Noi Ton Nintet, 41, when several gunshots were heard and a fight broke out with guards.
One officer suffered a stab wound in the fracas.
The trio then fled into a waiting bronze Isuzu pickup truck.
The injured policeman, Captain Thanameth Potiphan, was rushed to hospital and is in critical condition.
Police described the fugitives as ''extremely dangerous'' and set up checkpoints and roadblocks in the area.
Lieutenant General Nanthachart Supamongkhol said the U.S. Embassy had been contacted and all border points were on alert.
He added: ''The three prisoners who escaped were all in chains at the time.
We are investigating how they had weapons with them.
''Officers are checking CCTV to trace the escape route and find the fugitives.'' Police now believe that the fugitives are being helped to lay low in a remote area, before fleeing through one of the country's notoriously porous borders.
Arrest warrants have been issued for attempted murder of a policeman, escaping while being in custody, threatening others with guns, illegal possession of firearm and ammunition, carrying a gun in public without reason and shooting in public without reason.
Lieutenant General Nanthachart added: ''The fugitives are extremely dangerous and should not be approached by members of the public.
''We cannot determine how the prisoners received a 9mm pistol but if we find any accomplices they will be punished severely.'' Police arrested the couple in July this year after raiding their apartment where they allegedly found 1kg of crystal methamphetamine, a pistol with 200 bullets, scales, plastic bags and 205,000 Baht (6650 USD).
Helmus allegedly ordered the drugs from the 'dark web' before selling them to customers around the Thai 'Sin City' resort.