GREENSBORO, N.C. (AP) _ Classes at two Greensboro schools have been canceled after water tested positive for E.coli.

Guilford County Schools announced Wednesday that Bessemer Elementary School and Gateway Education Center will be closed on Thursday out of an abundance of caution while the city retests water in the surrounding area to make sure it is safe to drink.

A statement posted on the system’s website said the schools are expected to reopen on Friday.

The city said 13 homes have also been impacted.

Workers took samples from a station on Wednesday. The city said it has isolated the area’s water system from the rest of the city system. Crews are also working to install temporary water lines that should be installed by midnight Thursday.