LANZHOU - Five construction workers who were buried in a tunnel collapse on Wednesday in Northwest China's Gansu province are alive, rescuers said Thursday.

The rescuers have been trying to release the trapped workers since the collapse, which occurred around 2:50 pm at a railway tunnel that was under construction in the provincial capital Lanzhou, a spokesman with the rescue headquarters said.

They have made contact with the trapped workers with words clearly heard by each other, the spokesman said.

A channel with a diameter of 14 cm has been dug for rescuers to deliver food and water to the workers, with more experts expected to help with rescue efforts.

The cause of the accident is under investigation.