The incident in Shahberi village took place late on Tuesday, apparently due to "too much moisture in the walls of the basement and poor construction material used", an official told IANS.
Three persons, including the builder Ganga Prasad Dwivedi have been taken into custody, he added.
There were a dozen families living in the two buildings and it is feared that more than 50 persons, including labourers were still buried under the debris.
The National Disaster Response Force (NDRF) teams that had reached the spot immediately have pulled out three bodies from the rubble so far, the official added.
A state government spokesman said Chief Minister Yogi Adityanath has directed the District Magistrate (DM) to expedite the rescue and relief operations and ensure stringent action against those found guilty.
District Magistrate B.N. Singh, Superintendent of Police (Rural) Ashish Srivastava along with policemen from six police stations and NDRF teams requisitioned from Ghaziabad have been at the disaster site since the accident.
The rescue operations were hampered at night due to poor visibility. Union Minister and Noida Lok Sabha MP Mahesh Sharma also visited the crash site.
Rescue dogs, two hydraulic cranes and six bulldozers have been pressed into service to rescue the people trapped inside the debris.
An official told IANS that both the building had been built illegally and construction work on one had been completed after which a dozen families had shifted in it. The other was still under-construction.