Indian rescuers work on a site after a multi-storey building collapsed following heavy rain near Kumarhatti, Himachal Pradesh. AFP

• Four million people were forced out of their homes
  

• Assam and Bihar have been among the worst hit

• Weather office forecast widespread rain across Assam and Bihar

Over 100 people were killed as torrential rain in the initial days of monsoons wreaked havoc across India, Nepal and Bangladesh. Around four million people were forced out of their homes in the countries.

Assam and Bihar have been among the worst hit. TV footage showed roads and railway lines in Bihar submerged.

Situation in Assam worsened overnight with the Brahmaputra River breached its banks and flooded the nearby areas.

• Watch how a Pakistani TV journalist reports floods from submerged waters

• Assam floods kill 3 thousands affected

Assam’s infamous, the Kaziranga National Park was underwater. There were reports of four people drowning.

Villagers use a makeshift raft to cross a flooded area on the outskirts of Agartala. Reuters

"The flood situation has turned very critical with 31 of the 32 districts affected," Assam Chief Minister Sarbananda Sonowal told reporters.

"We are working on a war footing to deal with the flood situation."

Army Deployed

Assam, known for its tea industry, is hit by seasonal flooding each year, and the state and federal governments have spent millions of rupees on flood control.

Army and paramilitary personnel have been deployed across the state for rescue and relief operations and makeshift shelter camps have been set up, while the airforce is on standby, Keshab Mahanta, Assam's water resources minister, told reporters.

A girl carries drinking water in Morigaon district of Assam. AFP

The Indian weather office has forecast widespread rains across Assam and Bihar over the next two days.

In neighbouring Nepal, 64 people were killed and 31 were missing, with around a third of all districts hit by heavy rains, authorities said. Many of the deaths were caused by landslides that swept away houses.

In southeast Nepal, water levels on the Kosi River, which flows into Bihar, had receded, an district official said.

Since early July, flooding and landslides have damaged thousands of shelters at the refugee camps, killing two people, including a child, Human Rights Watch said in a release last week.