New Delhi — Investigators in India have found the second “black box” — the cockpit voice recorder — at the crash site of Air India flight 171, the Boeing 787-8 Dreamliner that slammed into buildings in the western city of Ahmedabad on Thursday, killing all but one of the 242 people on board and dozens more on the ground.

“The Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) have been located and secured,” an official from Prime Minister Narendra Modi’s office said in a statement late on Sunday.

The hope is that the voice recorder will help investigators piece together what caused the plane to crash just minutes after it took off from Ahmedabad Airport. The cockpit voice recorder captures audio from the cockpit, including conversations between pilots, alarms and ambient sounds.

A mayday call was sent by the flight captain, Sumeet Sabharwal, seconds after the London-bound plane left the runway in Ahmedabad.

Rescue workers and investigators recovered the other black box, the flight data recorder, on Friday. That recorder logs reams of data from the various systems on modern passenger jets, everything from altitude and speed to engine performance. Black boxes are designed to survive crashes and are considered vital to air accident investigators in determining the cause of disasters.

India’s Aircraft Accident Investigation Bureau (AAIB) is leading the probe into the Thursday crash of flight 171. They are being assisted by teams from the U.S. and the U.K. A team from the U.S. National Transportation Safety Board surveyed the crash site in Ahmedabad on Sunday. The Hindustan Times newspaper reported that representatives from the U.S. Federal Aviation Administration had also surveyed the crash site.  

“The AAIB has launched a detailed investigation, and the U.S. National Transportation Safety Board (NTSB) is conducting a parallel probe under international protocols since the aircraft is American-made,” Prime Minister Modi’s office said in a statement on Sunday.

India’s government also established a high-level committee specifically to investigate the crash and to recommend any changes deemed necessary to standard operating procedures going forward. That committee held its first meeting Monday.

At least 33 people were killed on the ground as the Air India plane crashed into a building that housed students from a medical college next door.

As the investigations into one of the worst accidents in India’s aviation history continued, the families of hundreds of victims were still waiting to have their loved ones’ remains returned to them.

The plane went up in a massive ball of flames and much of the fuselage was reduced to rubble, making it difficult for authorities to retrieve and identify bodies. Officials have been working to match DNA samples from crash victims’ remains and family members since late last week.

CBS News saw several families of victims at the Civil Hospital in Ahmedabad waiting for the bodies of their loved ones. The remains of at least 24 people had been handed over to their families as of Monday, authorities said.

“It’s a long process and it will take its own time,” Ahmedabad Police Commissioner G S Malik told CBS News on Monday. He said the final death toll would only be confirmed after all DNA testing was complete.

“Over 400 family members have reached Ahmedabad and are being assisted by our teams on the ground,” Air India said in a statement on Sunday.

India’s Directorate General of Civil Aviation told Air India to carrying out additional safety checks on all of its Boeing Dreamliner fleet last week.