At least three police personnel, including a station house officer (SHO), were seriously injured when sand smugglers attacked them at Hajipur in Vaishali district, around 20km north of Patna, late on Thursday night.

While the critically injured SHO of Hajipur Sadar police station Chitranjan Thakur has been referred to a private hospital in Patna, assistant sub-inspector Yugal Kishore Singh and constable Lal Babu Singh are undergoing treatment at Hajipur Sadar hospital.

The incident took place around 10.30pm, when a team attached to Hajipur Sadar police station raided a makeshift house storing sand illegally for sale. As soon as police reached the spot, 20 people attacked them with iron rods and bamboo sticks. Three cops suffered serious injuries. The attackers, however, managed to escape under the cover of darkness. Later, officers from neighbouring police stations rushed to the spot and admitted the injured to the local government hospital at Hajipur, around 3km away.

Hajipur additional superintendent of police (SP) Ajay Kumar said the team had gone to the spot on Hajipur-Lalganj road following a tip-off that illegal sand was being transported to different places from the depot. The 20-km stretch between Hajipur and Lalganj has turned a safe zone for sand smugglers.

The notoriety of the locality can be gauged from an incident dating back to 2006, when criminals had hurled crude bombs on the official car of then district magistrate of Vaishali Sanjiv Kumar Hans. The district magistrate, however, had survived the attack.

The Hajipur additional SP said efforts were on to ascertain the identity of the attackers, who were not happy with the police operation against illegal sand-lifting and transportation in the region. 'A few suspects have been detained for interrogation,' he told The Telegraph over phone on Friday.

Sand mining has been stopped across the state till September and the authorities have launched a crusade against the sand mafia. 'The lucrative business has attracted people with muscle and firearms. The estimated business of sand mining in Bihar is worth around Rs 6,000 crore,' said a source in the mines and geology department.

In August, deputy inspector-general (central range) Rajesh Kumar ordered a special drive against sand mining during which over 50 arrests, including that of influential people, were made from Patna and Nalanda districts.

Similar raids were also conducted in Saran, Bhojpur and Vaishali districts. Sand mafia had attacked Saran district magistrate Harihar Prasad near Sonepur when he went there to remove a road blockade local residents had put up at the behest of sand smugglers. Over a dozen country-boats, which were engaged in transportation of sand, were also seized.

Existing rules prohibit sand mining across Bihar between July and September, as rivers are in spate during monsoon. However, sand mafia continues operations in violation of rules. In Bihar, mining leases have been issued to 25 firms only.