In the second mishap in as many days, six persons were injured on Monday when cranes carrying out debris clearance operation at the site of the metro accident collapsed.

The incident comes a day after six persons were killed when an under-construction bridge of the Delhi Metro gave way at South Delhi's Jamrudpur.

Metro authorities said the crane mishap was caused due to a mechanical fault and that heavier cranes would be used from now on.

Metro chief E Sreedharan, who had resigned on Sunday taking moral responsibility for the accident, reached the site for the second time in the day following the mishap which occurred at around noon.

Doctors at the AIIMS trauma centre said six persons were brought to the hospital from the accident site with minor injuries.

However, DMRC officials said no one was hurt.

Four cranes were launching the girder when one of them malfunctioned apparently leading to the transfer of load to the others.

The officials said the crane operators miscalculated the weight of the launcher and this led to the accident.

Police has cordoned off the site.

The launcher also collapsed along with the two cranes when its wires snapped, eyewitnesses said.

Workers carrying the clearance operations were seen running to safety when the cranes came down.