CRPF Constable Ajit Singh fired shot dead the three colleagues inside a camp in Battal Ballian area on Wednesday night after a heated exchange of words, a police officer said.
The blast occurred on Thursday at the Chenjiagang Industrial Park in the city of Yancheng, in Jiangsu province, and the fire was finally brought under control at 3.00am on Friday (1900 GMT), state television said.
Survivors accused traditional Dogon hunters of carrying out the deadly raid in Ogossagou, according to Boubacar Kane, the governor of Bankass district which covers the village.
The Akbar Express, heading to the western city of Quetta from Lahore, crashed into the freight train in the Sadiqabad area of Punjab province's southern Rahim Yar Khan district, destroying five carriages and trapping passengers.
The Syrian regime and Russia have stepped up their deadly raids on the Idlib region since late April, despite an international deal intended to prevent a full-scale offensive on the area of some three million people.
Demonstrators gathered in major cities under the slogan "defending the peace" to denounce the deaths. 462 campaigners have been killed since 2016, according to the country's ombudsman.
The ministry said Ahmed Qura, 23, died "as a result of wounds sustained (from) the Israeli occupation forces' fire" on Friday.
The "Justice First" marches were called by the Sudanese Professionals' Association, which has been spearheading the protests since December.
Thirty-six others were injured, some of them critically, in a blaze that sent people scrambling up the stairs toward the roof in a desperate — and futile — attempt to escape.