The death toll from massive flooding and mudslides in northeastern India's Assam state rose to 62 on Sunday due to weeks of severe rains that caused one of Asia's largest rivers to overflow.

According to Assam's disaster management agency, more than 3 million people were displaced as the swelling Brahmaputra River overflowed its banks and inundated 32 of the state's 35 districts. Rescue efforts required the participation of the Indian army while the air force stood on standby.

During its roughly 800-kilometer (497 miles) trip through Assam, the Brahmaputra flows from Tibet in China through India and into Bangladesh.

Sunday, four persons were missing when a boat carrying nine capsized in the Dibrugarh region of eastern Assam, 500 kilometers (310 miles) east of the state capital of Gauhati. Strong currents, according to the police, are hindering ongoing search activities.

Forecasters anticipate a break in the weather after days of nonstop precipitation.

Assam's chief minister, Himanta Biswa Sarma, toured flood-affected districts on Saturday and called the situation dire.

"We are now focusing on relief and rescue operations," Sarma said, adding that the army and other rescue organizations have evacuated more than 20,000 people.

The region experiences annual monsoon rainfall from June through September. The rains are essential for seasonally planted crops but can cause extensive damage.

Flooding from swollen rivers has also spread to Bangladesh. The administration has warned that the situation will likely worsen in the worst-affected Sunamganj and Sylhet districts in the northeast and north.

Since Friday, lightning strikes have caused at least nine deaths in Bangladesh.