Helicopters and divers scoured the waters off India’s financial capital of Mumbai on Thursday in a search for survivors of a freak boat accident that killed at least 13 people a day earlier, three navy personnel among them, officials said.

A naval speedboat lost control and collided with a privately owned vessel taking tourists to the nearby Elephanta caves, famed for their rock art. The ferry capsized as a result, but 114 people were rescued.

Of those rescued, 97 were stable and four were in critical condition, while 13 bodies were recovered, the municipal corporation said on messaging app WhatsApp.

Navy and coast guard vessels joined in to search the harbour for at least two people still believed to be missing, an adult and a child, said a naval officer, who sought anonymity as he was not authorised to speak to the media.

The officer said the accident happened during the trial of a new type of engine for the speedboat.

“It appears that the engine got stuck at maximum throttle but we will know better once the inquiry is completed,” the officer told Reuters.

A naval spokesperson did not immediately respond, when asked for comment on the remarks.

Television channels showed a speedboat with at least five on board crashing into the passenger vessel.

Water started gushing into the privately-owned Neelkamal as soon as it was rammed, witnesses said, and passengers scrambled to don life jackets before jumping into the water.

Prime Minister Narendra Modi offered condolences to the bereaved, offering relief payments of 200,000 Indian rupees ($2,400) to the next of kin, and 50,000 Indian rupees ($600) for each of the injured.

“The boat mishap in Mumbai is saddening,” he added in a post on X on Wednesday.

The caves, which are Unesco world heritage sites dating from the fifth and sixth centuries AD, are thronged by tourists who make the roughly hour-long journey in boats from the Gateway of India monument at the city’s southern tip.