A portion of a housing society's boundary wall collapsed here on Tuesday morning, killing four construction workers and injuring eight, police said.
All 12 who had been buried under the rubble while repairing a drain adjoining it at the Jal Vayu Vihar in Sector 21 around 10 am were labourers, they said.
A team of Sector 20 police station later detained a sub-contractor, Gul Mohammad, who supplied labourers for the job, an official said.
