Five security personnel were killed and 14 others injured in Chhattisgarh’s Narayanpur district on Tuesday after suspected Maoists allegedly attacked their bus with an improvised explosive device, The Indian Express reported. The officials were part of the District Reserve Guard.

The explosion took place when the security personnel were returning from an anti-Maoist operation, PTI reported, citing Chhattisgarh Director General of Police DM Awasthi. He added that more than 20 security personnel were on the bus.

“Fourteen men have suffered injuries including three who have been critically injured,” Bastar Inspector General P Sundarraj said. “They have been airlifted and are being taken to Raipur for further treatment.”

The deceased were identified as head constables Pawan Mandavi, Jaylal Uike, constables Sevak Salam, Karan Dehari, who was driving the bus, and assistant constable Vijay Patel, according The Indian Express.

The 45th Battalion of the Indo Tibetan Border Police was helping in rescuing the injured, according to NDTV. The entire area was cordoned off, and a search operation was being carried out.

Chhattisgarh Chief Minister Bhupesh Baghel expressed grief about the incident. He also directed officials to ensure proper medical treatment to those injured in the incident. The chief minister said Maoists are frustrated as they are losing their ground due to continuous operations by security forces in the region. “This act is the outcome of their desperation,” he wrote on Twitter.