Rescue workers in India battle to save the lives of 19 people trapped under collapsed building in Maharashtra state

Rescue workers in western India are hopeful that they can save 19 people still trapped under the rubble of a five-story apartment building that collapsed Monday evening in the state of Maharashtra.

State and federal first responders are using specially trained dogs to help dig through the remains of the structure, which is located in Raigad district's Mahad city, about 150 kilometers (93 miles) south of Mumbai, and believe that it's possible survivors still remain.

The building collapsed at about 6:30 p.m. on Monday. The third, fourth and fifth floors were all "completely collapsed," according to Anupam Srivastava of India's National Disaster Response Force (NDRF), but officials are hopeful that air pockets in the parking lot and on the first floor have allowed people to survive.

Residents told emergency workers that when they ran out of the building, the pillars in the parking lot were "still vibrating," meaning they could have withstood the collapse.

Srivastava said "it is possible that the first floor may be intact," but that responders "can't see it below the debris."

"We expect the people who are trapped to be on the first or second floor or in the parking of the building," Srivastava said. "We are going through the vents and are using the canines to check, they smell live victims so if someone is trapped in the debris it will indicate it to us."

An official with the local fire department, V.Y. Mote, said he expects the operation to take one more day.

Up to 60 people are believed to be trapped after the five-story building in Mahad city collapsed.

Twenty-five people were able to flee the building before it collapsed, while eight people have been rescued from the wreckage since. One man who was injured by falling debris later died of a heart attack while in the hospital, according to officials.

The building was made up of 41 apartments, but 18 of them were not occupied, district official Nidhi Chaudhary told reporters. Local authorities have prepared a list of the building's residents and "have shared the details of the missing persons with those present at the scene of the collapse in case they are able to identify someone from among the injured," Chaudhary said.

Authorities initially feared that up to 60 people were trapped and 18 were injured, but have since revised those figures.

Monsoon rains trigger tea plantation landslide in India's Kerala state, killing at least 43 people

It's unclear what caused the building to collapse. August is monsoon season in India, when intense rains and floods wreak havoc on infrastructure, but authorities also appear to be investigating negligence. An initial police report has been filed against five people -- including the individual whose company built the building -- for culpable homicide not amounting to murder, but no arrests have been made.

Prime Minister Narendra Modi said on Twitter he was "saddened" by news of the collapse and that his "thoughts are with the families of those who lost their dear ones."

"I pray the injured recover soon. Local authorities and NDRF teams are at the site of the tragedy, providing all possible assistance," his office tweeted.

Following initial reports of the incident, the Twitter account for the office of Maharashtra's Chief Minister Uddhav Balasaheb Thackeray tweeted: "CM Uddhav Balasaheb Thackeray spoke to MLA @BharatGogawale and Collector Nidhi Chaudhary to inquire about the building collapse in Mahad. He has assured them that all possible support will be extended for speedy rescue & relief works."

India's home affairs minister, Amit Shah, tweeted: "The collapse of a building in Raigad, Maharashtra is very tragic. Have spoken to DG @NDRFHQ to provide all possible assistance, teams are on the way and will be assisting with the rescue operations as soon as possible. Praying for everyone's safety."

CNN's Joshua Berlinger and Swati Gupta contributed to this report.