Police say a tourist boat that capsized off India's remote Andaman and Nicobar islands was overcrowded and may have hit a rock before it went down. At least 21 people were killed.

Mohammed Rafique, the duty officer in Port Blair, said Monday that the boat capsized about 300 feet (100 yards) from shore Sunday afternoon. He said the investigation so far suggests the boat hit a rock.

Forty-seven people were on board, all of them Indian tourists. The passengers exceeded the boat's capacity, Rafique said. He had no further details.

India's president released a statement expressing "shock and grief" over the accident.

Boating accidents are common in India as many ferries are poorly built and often overcrowded, with little regard for safety regulations.