Singhewala (Muktsar), May 31 -- Five migrant workers from Uttar Pradesh were killed and 28 were injured when a blast ripped through an illegal firecracker manufacturing and packaging unit and brought the two-storeyed building down on the outskirts of Singhewala village in Lambi sub tehsil of Punjab's Muktsar district early on Friday, police said. The blast occurred around 1 am in the two-storeyed factory located in a field adjoining the Singhawali-Kotli road bordering Haryana, Lambi deputy superintendent of police (DSP) Jaspal Singh said, adding that migrant labourers worked at the unit. Those killed were identified as Shailender Kumar and Rahul of Hathras, Neeraj and Danveer of Aligarh and Akhilesh of Faizabad, all aged between 18 and 20, said officials. Muktsar deputy commissioner Abhijeet Kaplish said the injured were rushed to the All India Institute of Medical Sciences (AIIMS), Bathinda, and civil hospital at Badal village in Muktsar. "The blast occurred in one of the rooms in the factory, leading to the roof collapsing. Rescue work was complete by noon. Most casualties have been due to the damage to the building and not by the fire," Muktsar senior superintendent of police (SSP) Akhil Chaudhary said, adding that factory owner Tarsem Singh has been arrested. "A first information report (FIR) was lodged under Sections 105 (culpable homicide not amounting to murder), 118 (2) (voluntarily causing grievous hurt by dangerous means) 3 (5) (a criminal act done by several persons WITH common intention), Explosive Act and Factories Act. More arrests are likely based on the further probe," said the SSP. Malout sub-divisional magistrate (SDM) Jaspal Brar said all the hospitalised workers are out of danger and added that the cause behind the blast is under investigation. Additional deputy commissioner Gurpreet Thind said that two patients suffered head injuries and they will be operated at the Bathinda AIIMS. "All injured are out of danger," he said. Most workers injured in the roof collapse belonged to Hathras district of Uttar Pradesh and had joined work less than a fortnight ago. Manoj Kumar, a survivor, who rescued several workers, said they were sleeping on the factory premises after work when a loud explosion shook the area. "I woke up to shouts that a fire had broken out. There was smoke near the production unit and within seconds, there was a deafening sound and a power outage. I had to muster the strength to stand firm on the ground. Immediately thereafter, I started looking for my fellow workers but it was pitch dark. Our labour contractor, Raj Kumar, helped me rescue some of the victims," Manoj said at the civil hospital in Badal village. Another worker, Arun Kumar, from Shahjahanpur district, said all semi-skilled workers came to Muktsar district in search of a livelihood but the incident had left several of them badly injured. "We were all hired by Raj Kumar, who is also a native of Hathras. He is absconding now and his phone is switched off," he said. He said the police and other officials reached the site soon after and launched a rescue operation. Ganesh Kumar, a worker who suffered a fracture in the right leg, was worried about the medical expenditure. "I was sleeping in the front portion of the building that opens to a road when the explosion took place. Entry to the packaging area of the production unit was restricted," he said. Another worker, identified as Rinku, said two structures of the factory had been reduced to debris within seconds. "We had no idea if the factory was running legally or not. The entire area was razed to the ground within five minutes. We heard cries of help as power supply was disrupted due to the explosion," he added. Located in a field at a distance from the residential area of the village, the factory was unauthorised. Police sources said local resident Tarsem Singh was operating the factory for the past four months. Officials said it was baffling how the factory operator managed to buy a huge volume of explosives and other material used in producing firecrackers without permission. Even after 10 hours of the explosion, the smell of potash emanated from the debris. Scattered building material of two concrete structures, mangled iron rods in the ceiling and girders around the premises spoke about the impact of the explosion. A team of forensic scientists gathered samples, while teams of the police and fire brigade safely took out the stock of packaged fireworks from the factory site. A resident of Fatuhiwala village, Jasbir Singh, who owns an adjoining farmland, said that earlier the factory housed a water-packaging unit. "Tarsem unsuccessfully tried setting up a poultry farm and then an RO (reverse osmosis) water treatment policy. After failing in both ventures, he started the firecracker factory. I have no idea if it was a licensed unit," he said. DC Kaplish said he had received similar inputs from his field team. "Tarsem Singh had applied to obtain a license for running a cracker manufacturing unit in March. The permission was not granted as the stringent safety clearance was not accorded to him. Strict action will be initiated for violations that led to the loss of several lives," he said. The DC said that the Muktsar district police would be asked to probe how and where the factory operator sourced the explosives used for manufacturing the crackers. Doctors at the civil hospital at Badal said 13 patients were admitted to the hospital, while eight were referred to AIIMS, Bathinda. "There are minor patients, one of them is 10 years old, while two others are 15 and 16 years old," a doctor said. An official of the Muktsar district administration said that five bodies have been kept at the mortuary at the civil hospital in Gidderbaha. According to a medical bulletin released by AIIMS, Bathinda, 28 patients were brought to the department of trauma and emergency for medical attention. Of these, 17 patients arrived directly at the Bathinda institute while 11 were referred from the civil hospital, Dabwali, following initial triage and stabilisation. "A total of 21 patients were found to have sustained minor injuries such as superficial wounds, minor abrasions, and soft tissue trauma. These individuals were treated and subsequently discharged with instructions for outpatient follow-up and home care," reads the statement. Four patients were diagnosed with orthopaedic injuries, of which one patient sustained fractures of the femur and humerus. Another patient had a humerus fracture....