GAUHATI, India — Rain-triggered floods and mudslides have left a trail of destruction across northeastern India, killing at least a dozen people and affecting over a million, officials said Saturday.

Two schoolchildren were killed and several others injured earlier in the week near the town of Tawang when a wall from their boarding school collapsed as they were sleeping. Tawang, located in Arunachal Pradesh state, is perched at an altitude of 2,900 meters (9,500 feet).

Also in Arunachal Pradesh, a 36-year-old woman was swept away and three other people were killed when their car skidded and fell into a gorge. Six others were killed in neighboring Assam state.

“My appeal to people is to be on alert and those living in lowlands should move to safer higher grounds,” said Pema Khandu, chief minister of Arunachal Pradesh, the state closest to China’s Tibet region.

Arunachal Pradesh’s home minister, Bamang Felix, said disaster management agencies as well as police and paramilitary officers have been put on alert, and residents have been advised to avoid unnecessary travel.

Assam’s State Disaster Response Authority said around 900,000 people spread over 21 of the state’s 33 districts have had their homes submerged. Several thousands are living in government-run relief camps in the state.

Elsewhere in Assam, Kaziranga National Park, home to the endangered one-horn rhinoceros, has been flooded. The park is located 225 kilometers (140 miles) east of Gauhati, the state capital.

“The rhinos and other animals are taking shelter in artificially created higher ground or have crossed the highway to higher areas,” said Jukti Borak, a park official.

Authorities have prohibited vehicles from speeding on the highway that runs along the park. Apart from the estimated 2,500 rhinos, Kaziranga is home to a variety of wild animals that cross the highway in search of higher ground during floods.

Floods and mudslides have also hit some other northeastern states, including Meghalaya, Sikkim and Mizoram. In Mizoram, floods have submerged about 400 homes in the small town of Tlabung, police said.

Hydrologists and conservationists expressed grave concern over the situation.

“In the end, this is a clear case of climate change impacting on our ecosystem,” said Nayan Sharma, a prominent hydrologist and professor at the Indian Institute of Technology Roorkee.