BHUBANESWAR, India (Reuters) - The death toll in an Indian coal mine collapse rose to 16 on Saturday and could rise further, officials said, as some people are still feared trapped at a coalfield run by state-owned Coal India Limited.

The accident occurred in Jharkhand state on Thursday evening at the Lalmatia mine, one of the country’s largest, which is owned by Eastern Coalfields Limited (ECL).

“At night (on Friday), the rescue operation was slow due to fog,” R.R. Amitabh, a senior officer at ECL, told Reuters, adding that about 30 percent of the collapsed mine waste had been removed.

Coal India has a poor safety record, with 135 accidents reported last year, killing 37 people and injuring 141, the company said in a report.

Operations at the mine in Godda district, about 280 km (175 miles) from the state capital, Ranchi, have since been stopped, Amitabh said.

The state police spokesman R.K. Mullick said the number of people still trapped may be less than the nearly two dozen assumed earlier, based on the number of families who were searching for their kin.

The mine has an annual capacity of 17 million tonnes and accounts for about half of ECL’s coal production. Last month, ECL accounted for about 9 percent of Coal India’s total production of 50 million tonnes.

The federal coal ministry has ordered an investigation and announced some cash compensation to the families of miners who died in the accident.