Devastating floodwaters and landslides triggered by intense monsoon-season rains have killed at least 335 people across the disputed Kashmir region over the past few days, with Indian and Pakistani troops working to rescue tens of thousands of stranded people, Reuters reported.

Following six days of rain in the region's worst flooding since 50 years, the death toll in Pakistan is 205 as of Monday, according to Pakistan's National Disaster Management Authority. In Indian-controlled Kashmir, the toll has reached 150, according to the Ministry of Home Affairs.

While 450 villages have been submerged and 2,000 others have been affected by floods, all schools and offices have been shut down since electricity and drinking water supplies have been limited across the region, CNN reported.

After much of the state's capital, Srinagar, was submerged, forcing thousands to move to rooftops, army units equipped with helicopters and boats have rescued 20,000 people in India's Jammu and Kashmir state, India's Ministry of Defense said Monday.

Although the rains had stopped Sunday, the spreading water from the overflowed Jhelum river was moving too fast to allow boats to reach many of the residents in Srinagar, officials said. By Sunday evening, however, several boats had been deployed to start rescue efforts, said Omar Abdullah, Jammu and Kashmir state's top elected official.

Thousands of police officers and army rescue workers were also fanned out across Jammu and Kashmir to help with relief and rescue efforts, according to UK MailOnline.

Meanwhile, the prime ministers of India and Pakistan offered to help each other amid the emergency relief efforts and each overflew their parts of Kashmir to view the damage.

Indian Prime Minister Narendra Modi surveyed the flood-hit areas over the weekend to assess the situation, promising the state federal help to deal with the devastation, which he immediately declared as a "national-level disaster."

Modi also offered help to Pakistanis living across the border in Pakistan-administered Kashmir, which has also been lashed by heavy rains and flooding, according to CNN.

"It is a matter of great distress that the retreating monsoon rains have played havoc in many parts of our two countries," he wrote in a letter to Pakistani Prime Minister Nawaz Sharif, adding that "the devastation caused by the record rains and the consequent flooding is unprecedented."

"While reviewing the situation in Jammu and Kashmir, I was informed that the damage to life and property is equally, if not more, severe in areas across the 'Line of Control' as well. My heart goes out to the affected people and my deepest sympathies are with them and their families."

"In this hour of need, I offer any assistance that you may need in the relief efforts that will be undertaken by the Government of Pakistan. Our resources are at your disposal wherever you need them."

In the meantime, 95 relief camps had been set up for those displaced by the flooding.

India and Pakistan have fought three wars over Kashmir and shoot-outs between the country's armies along the "line of control" are frequent.