Newark city officials are trying to figure out what has killed hundreds of fish at a local lake over the past week or so.

Several hundred fish, mostly carp, have died at Lakeshore Park and the leading theory is that low oxygen levels are the likely culprit, said Newark Director of Public Works Soren Fajeau.

The city has hired a water quality specialist to take samples and help evaluate exactly what is gone wrong, Fajeau said.

“We’re waiting for some lab results to come back that can hopefully shine a light on what the problem is,” he said.

The lack of oxygen might be related to the recent high temperatures or a seasonal die-off of aquatic plants, Fajeau said, adding that increased algae levels could be to blame.

The city is adding fresh water to the 16-acre artificial lake and pumping air directly into the water in an effort to mitigate the problem.

It is also scooping up the dead fish so they can be hauled away and disposed of, Fajeau said.

“We hate losing fish like that,” he said. “It’s caused a lot of concern for folks and we certainly understand that.”

The city expects to have more definitive answers in the next week or two.