The New Balance shoe factory in Skowhegan will remain closed through the weekend after a number of workers were exposed to an unknown chemical solvent on Thursday afternoon.

The chemical incident caused symptoms including difficulty breathing, eye irritation, burning and tingling in about 30 employees, prompting the Boston-based shoe company to evacuate the plant and halt operations.

New Balance is continuing to work with authorities to investigate what happened and expects to reopen after the weekend, Raye Wentworth, New Balance’s Maine regional manufacturing lead, said late Thursday night.

Skowhegan Fire Chief Shawn Howard said about 70 employees used a tent set up for decontamination outside the factory, where they showered, changed clothes and stayed in school buses as Hazmat teams investigated.

Five people evaluated at Redington-Fairview General Hospital in Skowhegan due to their exposure to the solvent were released on Thursday night, Howard said.

Some 200-300 people were evacuated from the plant. All employees are safe, Wentworth said.

The plant in Skowhegan is one of three where New Balance manufactures shoes in Maine. The others are in Norridgewock and Norway.