MARTINSBURG, W.Va. (WDVM) — Just before 6 a.m. Monday a chemical tanker at the wastewater treatment plant on E. John Street accidentally intermixed with a chlorine composition triggering an ammonia odor which could be sensed for 20 miles from the city, according to officials.

By 8 a.m. evacuations had begun within a half-mile from the plant and traffic disruptions tied up motorists in downtown Martinsburg.

Several evacuation sites were set up, rotating locations, with Orchard View Elementary School being the fourth and latest.

Berkeley County Public Information Coordinator Chad Shifflett said that irritation from the vaporous emissions should result in only mild, temporary discomfort but medical attention should be sought if symptoms persistent.

By mid-afternoon Monday a team of chemical analysts were to have conducted tests to more accurately assess potential lingering consequences of the accident.

Emergency response teams were deployed to Martinsburg High School to prepare a public safety plan. They consisted of Berkeley County Sheriff and Fire Department personnel, Martinsburg city police and West Virginia State Police, assisted by a helicopter. The teams, by mid-morning, relocated to the county 911 center nearby.

Martinsburg Mayor George Karos said everyone appears to be safe from the accident. But with Christmas Eve approaching, the scare was most disruptive to start the holiday week.