SAMARINDA, Indonesia (AFP) - Two workers were killed and 13 trapped on Tuesday after a partially-constructed building collapsed on the Indonesian part of Borneo island, officials said.

Scores of construction workers fled the building site in the city of Samarinda in East Kalimantan province as the three-storey structure crashed to the ground in the early hours.

Rescuers pulled two bodies from the rubble following the accident, which happened just hours after work was finished on the third floor, local disaster agency chief Robby Hartono told AFP.

"Thirteen workers remain trapped under the rubble. We can still hear cries and groans," he said, adding that rescuers were struggling to shift piles of broken concrete and mangled metal.

Three people were pulled alive from the rubble and taken to hospital, he said.

Hartono blamed the building's weak foundations for the accident.