Residents who live near Belt Junior High School in Wheaton filed suit yesterday against Montgomery County officials, claiming the county violated state laws when it designated the abandoned school to be used for senior citizen apartments.

The suit, which was filed in Montgomery County Circuit Court against County Executive Charles W. Gilchrist and the seven County Council members, is the first time that the county's 1 1/2-year-old zoning law dealing with setting new uses for official facilities has been challenged, according to County Attorney Paul McGuckian.

The suit brought by 14 members of the school's neighborhood maintains that it is unlawful for the County Council to give the executive the authority to designate the new uses. The suit contends that only the council can make reuse and zoning decisions.

The future of the school building has been debated since it was closed in 1983. The council originally planned to convert the building into single-parent apartments. But after strong pressure from citizen groups, the council reconsidered and forwarded a list of recommendations for Belt to Gilchrist, who chose senior citizen housing 10 days ago.

Gilchrist said in response to the suit that "we think there is no problem" with the county's actions. Council President Michael L. Gudis said he would not comment on the lawsuit but said there is a "tremendous need" for housing for the elderly.

One of the neighbors, Carl Henderson, said the group wants the site to remain a school because it believes that the population in the area is growing and another school will be needed there. Neighbors also are concerned, he said, that designating the site for multiple-family use will open the possibility that other homes in the neighborhood could be switched from single-family housing, thus changing the character of their neighborhood.

Henderson said he is discouraged that the council did not consider other sites presented by his group for housing the elderly. "I get the feeling the council has just ignored everything we've said."

The residents also contend that the council has arbitrarily changed the zoning without giving neighbors the appropriate opportunity to voice their complaints.

Marilyn Piety, the former president of the Allied Civic Group, which has been active in the neighbors' campaign, said that although there were hearings on the issue, "none of the residents were notified as required by county law."

Attorney Norman Knopf, who is representing residents in the suit, said, "It's a noble goal to try to have housing for the elderly. But there are safeguards you have to follow no matter how noble the goal is."

Despite the lawsuit, some residents near Belt school expressed satisfaction with the county's decision to designate it for senior citizen housing.

Diana Jordan, who lives about 50 yards from the school, said she favored the plan. "I was very pleased when they closed the school," said Jordan, whose roommate has two children who attended Belt. "We had teen-agers getting out at 1 p.m. and hanging out in our yard, drinking, smoking and doing drugs.

"Our original thought was it would be great for a senior citizen complex or a youth center," Jordan added. "I wouldn't find that offensive and it would serve the community."