Phnom Penh CNN  — 

Cambodians have taken to the streets to mourn the death of a high-profile political commentator and government critic after he was fatally shot at point blank range.

Kem Ley was gunned down at a convenience station attached to a gas station Sunday morning, the Interior Ministry said in a statement. Local news reports said he was drinking his regular morning cup of coffee.

His death brought thousands onto the streets, with mourners surrounding a car containing his body as it drove through the center of the capital Phnom Penh.

Earlier, a furious crowd had prevented police from taking away the body, which lay on the floor of the Star Mart inside a Caltex petrol station for hours in a pool of blood, a witness, who didn’t want to be identified, said.

The body was eventually draped in Cambodian flag and taken away, the witness added.

Funeral rites, which begin immediately after death in Cambodia, are expected to last for up to a week. People lined up at his funeral Monday with lotus flowers to pay tribute.

Ley’s death comes amid tensions between Prime Minister Hun Sen’s government and opposition parties and civil society. He was the founder of the Grassroots Democracy Organization.

Police said that two men shot Ley at point blank range. The Interior Ministry said an assailant had been caught after trying to flee the scene.

The statement named him as Choup Samlap, a 38-year-old farmer. It said he was found in possession of a Glock shotgun.

“After questioning him, he said he lost some of his land because Kem Ley had not paid his debt to him. It is a $3,000 debt. But we don’t believe him yet, this is under investigation,” said Kirth Chantharith, a spokesman for the National Police.

The Interior Ministry said it would investigate Ley’s death and take action to prosecute the assailant and any other potential accomplices in accordance with the law.

The U.S. State Department said it was deeply saddened by his death and urged that the investigation into his death be “thorough and impartial.”

CNN’s Katie Hunt wrote from Hong Kong, journalist David Boyle reported from Phnom Penh