Officials are warning Howard County parents to keep a lookout for signs their children are involved in the increasing gang activity in the county.

Frank Clark, a gang intervention specialist with the Maryland Department of Juvenile Services, said parents need to be aware of what Howard County police describe as a growing presence of gangs in Howard, particularly the group known as Mara Salvatrucha or MS-13.

"We need to wake parents up to this fact: Gangs are real," Clark said. "It's not something that they need to continue to ignore."

The Howard school system is hosting a seminar Tuesday evening about gang activity in the county and how parents can tell whether their children are involved. Clark is the featured speaker.

MS-13, the largest gang in the Washington region, had a presence in Howard by 2001, when police officials made their first arrest of a known MS-13 member. The next year police arrested several members of the gang who committed crimes in the county. By 2004, police were investigating MS-13 for major crimes such as rape, robbery and assault.

"You don't normally think of gangs in Howard County," Lt. Mark S. Joyce, commander of education and training for the Howard County police, told a group of residents this week. "But Howard County does have gang elements in it. . . . MS-13 has a foothold."

The county has documented 57 incidents related to MS-13 and identified 55 MS-13 members who have been arrested or involved in criminal activity within Howard, Detective Kelly L. Smith testified to a congressional subcommittee investigating gangs in April.

The gang's presence in Howard is not considered as significant as in Northern Virginia, Montgomery County or Prince George's County, authorities said.

In addition to MS-13, the other prominent gangs in Maryland are the Bloods and Crips. "There are also a lot of smaller neighborhood gangs operating," Clark said, "but I couldn't even begin to name all those."

He said one indication that children might have joined a gang is an unexpected change in clothing. "Kids will all of a sudden only want to wear one particular color," Clark said. "The kids will only want blue or red or black clothes."

MS-13 members, for example, wear blue and white clothing.

Other signs of gang involvement include frequent use of the word "thug" and unusual drawings or writings, such as five- or six-pointed stars, pitchforks, the devil's hands with long fingernails, Clark said.

"A thing that a parent thinks is just scribbling might in fact be gang graffiti," he said.

Clark said parents should also monitor other hints that their children are involved with gangs: sudden changes in friends, dips in grades or discipline problems at school.

"A lot of parents believe in giving children their space and letting them have privacy," he said. "But I tell parents: You need to check on their rooms. You need to watch what your kids are doing."

The seminar, designed for students in grades five to 12 and their families, is scheduled for 7 p.m. at the Homewood Center on 10914 Route 108 in Ellicott City.