Assam Police on Friday launched a massive combing operation following stepped up violence by the ULFA, which carried out attacks in four places that left at least 32 people injured.
According to officials here, police launched a crackdown on suspected ULFA strongholds but no arrests have been made so far.
The ULFA mainly targeted policemen in Thursday's attacks, including a grenade attack at Mangaldoi town in Darrang district that injured 22 people.
In Dhubri district, an IED exploded near Purani police station in Golakganj area, injuring four people including a constable.
In the same district, a cyclist hurled a hand grenade inside a shop injuring one person while in Nagaon district, the militants targeted Haibargaon police station injuring five people including a policeman.
In view of the increased violence, special security pickets have been posted in and around key installations and railway tracks.
Police have reviewed security arrangements across the state and decided to step up vigil to prevent further violence.