Story highlights More than two dozen killed in two building collapses in India

A crumbling four-story building falls in New Delhi, killing 10 people

An 11-story structure topples in Chennai, killing 17 and trapping many others

Unauthorized permits, shoddy construction among factors in collapses

The death toll in two building collapses in different cities in India over the weekend has climbed to at least 27, with more victims still trapped in the rubble, officials said.

A crumbling and run-down four-story building in New Delhi collapsed Saturday morning. "Ten people, including five children and three women, died," Deputy Commissioner of Police Madhur Verma said. Two others were also injured, he added.

The building was around 50 years old and housed several families. Rescue efforts were hampered by cranes in the area. Officials suspect construction work at an adjoining building could be to blame.

Another building collapsed Saturday in Tamil Nadu state.

The 11-story structure under construction in the state capital of Chennai toppled over, killing at least 17 people, according to the National Disaster Relief Force (NDRF).

There are still many people unaccounted for, although authorities are unsure of the exact number. More than two dozen survivors have been rescued from under the debris.

"Fifty workers were believed to be present at the construction site at the time of collapse. Rescue operations are still on," said Chennai Police Commissioner Sebastian George.

S.P. Selvan, the deputy inspector general of the NDRF, said Monday it would take a couple of days to clear away all the wreckage.

The collapse in Chennai came amid heavy rains.

Building collapses in India are an all too common occurrence, and have killed hundreds of people over the past several years.

An official with the New Delhi Municipal Council told CNN many of the incidents occur because of unauthorized construction. People build extra floors in structures without permits, creating hazardous conditions. The official said there have been several buildings in New Delhi designated as dangerous, yet people continue to live in them.

Corruption is also a problem, which leads to the authorization of risky building permits. Other factors that contribute to the high number of building collapses in India include lack of oversight, poor quality building materials and even overpopulation.

A building collapse in January in the tourist resort of Goa claimed at least 14 lives.