This is the dramatic moment the grieving husband of a woman killed by a gunman who is still at large attacked the parents of the suspect.

Sompong Chantara, 53, lunged for the mother and father of Paiboon Jaiboon, 32, following the deadly rampage in Suphanburi, Thailand, this morning.

The gunman allegedly killed Sompong's wife, Chatarat, 50, along with Ramphoei Jaiboon, 67, and Somphas Jaiboon, 51, while Chutimol Klinhom, 68, was seriously injured.

Police said the murderer fled the scene and is yet to be caught. A school 50 metres from the shooting, where the gunman's son was having lessons, was put into lockdown with armed officers surrounding the classrooms, where panicked pupils hid.

Officers are interrogating the attacker's parents at the local station to try and trace him - sparking the angry outburst from the husband of the victim, who was in a land dispute with the suspected killer.

Sompong says in the video: 'My wife is dead, what have you done? What did she ever do to you?

‘This b*****d has a gun and shoots any people around. Shooting the entire family, what in the world. Kill him.'

Officers found 11 bullet shells from a .38 calibre firearm at the scene.

They surrounded the house for around 30 minutes before charging inside, but did not find the suspect. They fear he has escaped.

They said the attack was around 50 metres from Wat Yang Sawang Arom School, prompting teachers to bring pupils inside buildings for safety while officers guarded the area. They believe the suspect's son also studies there.

Police said that students are safe and should remain inside buildings, protected by six police officers.

The suspect allegedly opened fire on his neighbours in a dispute over land.

The suspect's aunt, Somphot Jaiboon, said she was unable to contact him and urged him to surrender.

She said that Paiboon and the victims had an ongoing dispute over an acre of land, which belonged to several siblings and could be passed down to their children.

Somphot allowed the suspect to build a garage on the land as it partially belonged to her, but the victims refused, which caused the conflict to escalate.