ROCKY MOUNT, N.C. (AP) — A major Pfizer pharmaceutical plant in North Carolina that makes critical supplies for U.S. hospitals has restarted production about 10 weeks after it was heavily damaged by a tornado, the company announced Monday.

Getting a majority of manufacturing lines at the Rocky Mount facility back up and running is a "proud achievement," Pfizer said in a statement. Full production across the facility's three manufacturing sites is expected by the end of the year.

Parts of the massive plant's roofs were ripped open and pallets of medicine tossed around when the tornado touched down on July 19. But most of the damage was to a storage facility for raw materials, packaging supplies and finished medicines, rather than its medicine production areas, Pfizer said. No employees were hurt.

The plant produces anesthesia and other drugs as well as nearly one-fourth of the sterile injectable medications Pfizer supplies to U.S. hospitals, the company said.

Thirteen medicines were prioritized based on patient need and inventory levels, and are now back in production on the lines that have restarted, Pfizer said. The medicines are expected to ship to distribution centers in the fourth quarter of this year. Although manufacturing has resumed, the company said some medicines may not be back in full supply until next year.