Five members of a family walked into their bank in Rockville yesterday to get money before going to work, but within a few minutes the family members -- most of whom do not speak English -- were surrounded by police, the target of an apparent practical joke.

Montgomery County police spokesman Harry Geehreng said officers were called to the bank by a silent alarm after the teller serving the family noticed that the back of their deposit slip had the words "This is a stick-up" written on it.

Geehreng said the Rockville family, two women and three men ranging in age from 20 to 40, apparently had no idea the message was there when they handed the deposit slip to the teller at the First American Bank in Congressional Plaza.

"They were totally in the dark," said police Sgt. Donald Mates. "We don't know if this was an abortive bank robbery attempt, where someone saw something and left before using the note, or if it's someone's idea of a bad joke."

Mates said the teller noticed the message, which was written in different ink from that used on the front of the slip, and sounded an alarm. By saying the bank was experiencing computer problems, she stalled the family members until police arrived.

County and city police surrounded the building within minutes of the sounding of the alarm. Police officers said that after they realized what happened, the family was released without being charged. Geehreng said police have no suspects.

Police would not identify the family, who are Asian, or their nationality. Only one member of the family speaks English, which prolonged the interrogation after the arrest, Geehreng said. Bank officials refused to comment on the incident, saying that it is policy not to discuss robberies or attempted robberies.