Police say the improvised explosive device detonated as a military convoy drove by.
A suicide bomber rammed an explosives-laden car into a convoy of military vehicles carrying Indian paramilitary officers in Kashmir on Thursday, killing at least 44 of them in the deadliest attack on security forces in the disputed region that could raise tensions with Pakistan.
Indian media reports said the Pakistan-based Jaish-e-Mohammed group had claimed responsibility for the attack that was carried out by a local resident.
A spokesman for the group said "the suicide attack" was carried out by Aadil Ahmad, alias Waqas Commando, in a statement sent to local newspapers.
Unconfirmed photos showed the charred remains of at least one vehicle littered across the highway, alongside blue military buses.
Senior police officer Muneer Ahmed Khan said the attack occurred as the convoy reached Pampore on the outskirts of the disputed region's main city of Srinagar. He said one bus was destroyed and at least five other vehicles were damaged by the blast.
Authorities blamed rebels fighting against Indian rule for the attack.
Khan said soldiers and counterinsurgency police reinforcements were deployed in the area and the injured were evacuated to hospitals.
India's foreign ministry demanded that its neighbour should act against militant groups operating from its soil.
“We demand that Pakistan stop supporting terrorists and terror groups operating from their territory and dismantle the infrastructure operated by terrorist outfits to launch attacks in other countries,” India’s foreign ministry said in a statement.
Pakistan condemned the attack.
"We have always condemned heightened acts of violence in the Valley," Pakistan's foreign ministry said in a statement.
"We strongly reject any insinuation by elements in the Indian government and media circles that seek to link the attack to the State of Pakistan without investigations," it added.
The attack was the deadliest on Indian forces in that part of Kashmir since September 2016 when 19 soldiers were killed in a pre-dawn militant raid on the Uri army camp.
India and Pakistan each claim the divided territory of Kashmir in its entirety. Militants have been fighting Indian control since 1989.
Most Kashmiris support the militants' demand that the territory be united either under Pakistani rule or as an independent country, while also participating in civilian street protests against Indian administration.
About 70,000 people have been killed in the struggle for control of Kashmir.
India has an estimated 500,000 soldiers in Kashmir, which has been divided between India and Pakistan and riven by unrest since the end of British rule in 1947.
New Delhi accuses Pakistan of fuelling the uprising that has left tens of thousands of civilians dead. Islamabad denies the charge, saying it only provides diplomatic support to Kashmiris' right to self-determination.
A report published by the US Senate Intelligence Committee last month had said that "cross-border terrorism, firing across the Line of Control (LoC), divisive national elections in India, and Islamabad’s perception of its position with the US relative to India will contribute to strained India-Pakistan relations at least through May 2019, the deadline for the Indian election, and probably beyond."
The report further said that "continued terrorist attacks and cross-border firing in Kashmir have hardened each country’s (India and Pakistan) position and reduced their political will to seek rapprochement. Political maneuvering resulting from the Indian national elections probably will further constrain near-term opportunities for improving ties."