The mode of Pulwama attack was indicated by a video Jaish had uploaded online.

Highlights Pak-based Jaish-e-Mohammed claimed attack that left 40 troopers dead

J&K police had spotted a threatening video from them

Video showed Afghan attack in which explosive-laden vehicle was used

The devastating attack on the CRPF convoy in Jammu and Kashmir, which cost 40 lives, had been preceded by what appears an intelligence failure.

Sources said the Pakistan-based terror group Jaish-e-Mohammad, which has claimed responsibility for ramming a car full of explosives into the 78-vehicle convoy, had warned of a suicide attack in Kashmir just two days ago.

The mode of attack was indicated by a video they had uploaded online.

The video showed an attack in Afghanistan, wherein an explosive-laden vehicle used.

Sources said the Criminal Investigation Department of the state police had shared the video and input about the possible attack with intelligence agencies.

No action, however, had been taken about it, sources indicated.

The Scorpio loaded with more than 350 kg of explosives had targetted the convoy on the Jammu-Srinagar highway. Driving down from the facing lane, the suicide bomber had rammed a bus carrying 39 CRPF personnel.

The massive blast that followed had ripped apart the bus. Another one was partially hit. The wreckage and human remains had scattered over a 100-metre stretch.

Without going into details, the government has promised action.

Prime Minister Narendra Modi tweeted, "The sacrifices of our brave security personnel shall not go in vain".

A more definite warning came from Union Minister Arun Jaitley, who tweeted, "Terrorists will be given unforgettable lesson for their heinous act".

Union Home minister Rajnath Singh is expected to visit Jammu and Kashmir tomorrow.