A total of 40 troops were travelling in a bus from Pushtola to Gatta, about 4 kms from here, for an operational duty when at around 1130 hours the blast took place, killing 12 of them.
Making a brief statement in Maharashtra Assembly, state Home Minister R R Patil said 12 CRPF personnel were martyred in the blast and 28 others wounded.
Of those injured, eight seriously wounded jawans were airlifted to Nagpur where they have been admitted to Wockhardt Hospital, Patil said, adding the rest were undergoing treatment at the Civil Hospital in Gadchiroli.
The daring daylight Naxal attack came even as CRPF chief K Vijay Kumar was on a tour of Maharashtra and was in Gadchiroli area.
Shortly after the blast, Kumar spoke on telephone to Union Home Secretary R K Singh in Delhi and briefed him about the incident, CRPF officials said.
Two helicopters were pressed into service for evacuating the troops to the hospitals, the officials said. A CRPF reinforcement team and men from the Maharashtra's anti-Naxal force were rushed to the attack site.
Patil told the Assembly that the CRPF chief as also DIG of Maharashtra's anti-naxal force V D Mishra visited the scene of the blast and also met the injured personnel in hospitals. He said the authorities were looking into the reasons that led to the unfortunate incident.
"We are inquiring into what actually happened...whether proper security procedure was followed," the minister said.
Earlier, reports reaching the CRPF headquarters in New Delhi had put the number of dead at 15, the officials said.