The bodies of two young brothers have been found in a Townsville river near a park where they liked to play.

About 100 people joined a desperate search for the boys, aged three and five, after they went missing from a Cranbrook home about 5.30pm on Monday.

The search ended in tragedy just before 6am on Tuesday when police found their bodies in the Ross River, near Cranbrook Park.

Officers issued an amber alert after relatives raised the alarm, saying the boys had failed to return home at the usual time.

“The boys apparently are regular visitors to the park but they haven’t come home at their usual time so family started looking for them,” Townsville Police District Duty Officer Senior Sergeant Ian Wilkie said on Monday night, while the search was still underway.

“When they were unsuccessful they contacted police.

The boys were caught by security cameras walking towards the park, on the banks of the river.

Police used air support and motorbikes to scour the area, including the banks of the river. They doorknocked homes in the hope the boys were simply lost and “curled up somewhere“, Snr Sgt Wilkie said.

Locals desperate to help joined the search.

One woman told the Townsville Bulletin police came to her door wanting to check their yard.

“They showed us photos of the children ... being a grandmother, I have a five- year-old grandson, I couldn’t go to bed and sleep on it so I got out and helped,” the woman said on Monday night.

Police have offered their condolences to the boys’ distraught family.