WASHINGTON (AP) _ Bell Atlantic disconnected, apparently accidentally, some circuits it uses to route AT&T calls to and from telephone customers in the District of Columbia.

Spokeswoman Sandra Arnette said the problem started Monday around 9 a.m. EST and lasted about four hours. During that time, Arnette said, AT&T customers calling to or from Washington might have encountered a message stating that all circuits were busy.

Arnette said the cause of the disruption was under investigation. She said human error appeared likely.