A jilted boyfriend was killed when a bomb he threw at his ex-girlfriend's house exploded in his face.

Heartbroken Surapong Thongnak, 36, was furious when Kanonraphat Saowakhon, 28, refused to reconcile with him in Surat Thani, southern Thailand.

The seething ex allegedly hatched a plan to kill Kanonraphat and prevent her from finding anyone else.

Surapong was seen standing outside the family's wooden home before pulling the pin on a grenade. However, the military device hit a concrete pillar on the property and bounced back.

Surapong picked up the grenade as it exploded in his hands, instantly killing him and injuring four others on May 25

Police arrived at the scene after being notified of the explosion at 8 am. They found lifeless Surapong lying face down in a pool of blood while debris and shrapnel were scattered across the yard.

Four people, including the ex-girlfriend, were wounded and rushed to a hospital where they were treated for minor injuries before being released.

Police Major Chinnakrit Sawatdiwong of the Tha Chana Police Station said: 'The injured individuals were taken to the Tha Chana Hospital.

'All of them have been discharged except for Samart Janyang, 68, who suffered more serious injuries. He has been transferred to the Surat Thani Hospital for further treatment.'

Residents said they were drinking coffee on the patio when Surapong arrived in a white car.

The eyeliner-wearing boyfriend was understood to have barged into the house and woke up his sleeping girlfriend, begging for her to take him back.

When she turned him down, he allegedly went berserk and tried to stab her with a pair of scissors. Her screams alerted her family, who intervened and managed to stop the attack.

Crazed Surapong reportedly stormed off to his sedan to grab a grenade. He pulled the pin and lobbed the explosive toward the home, prompting the residents to scatter.

Sayan Rodkird, the son of the homeowner, said: 'We ran away when he threw it toward the house, but it struck a pillar and bounced back toward him without exploding. He tried to pick it up, and that's when it detonated right in his face.'

Surapong's mother, Ranjuan Timdee, 58, said the couple had only been dating for two months before breaking up.

She said: 'Last night, he called to tell me he would try to patch things up with her. I was shocked to receive the news this morning that he had died. I couldn't believe he could be so violent.'

Police said they seized half a kilo (1.1 lbs) of meth from Surapong's car. They added they were investigating where he had obtained the grenade.