BANGKOK — The helmsman who operated a passenger boat that sank in a Thai river over the weekend has been arrested for violating navigation laws as the death toll climbed Tuesday to at least 27 people, an official said.

The search was continuing for two passengers known to be missing, a 2-year-old boy and a 70-year-old woman, said the Marine Department official, who spoke on condition of anonymity because she was not authorized to release information.

The boat was carrying over 100 Muslims home from a religious festival Sunday on the Chao Phraya river north of Bangkok. It sank rapidly after taking on water just a few meters from the riverbank.

Forty-four passengers were hurt.

Authorities previously said the passenger capacity was 50 and overloading was a suspected cause of the sinking.

The helmsman is suspected of allowing too many passengers onboard and having an expired license, according to the Marine Department.