Each morning these days, Lake Clifton High School Principal Oscar Jobe stations himself at the school door as students file in -- not so much to welcome them as to make spot checks for weapons in bags and parcels.

Jobe has good reason to worry: Two of his students were fatally shot at the school this academic year, victims of the city's much publicized epidemic of slayings among teen-agers.

Last October, 17-year-old Kevin Diggs was killed in the Lake Clifton yard in front of scores of students, allegedly during a fight with three young men who were not students there. Police have said the slaying may have been connected with a running argument Diggs had had with another student.

In the latest killing, Jan. 29, a 14-year-old student is accused of shooting 16-year-old Brent Jordan after an argument in a hallway. The younger student, who knew Jordan in junior high school, had transferred to Lake Clifton only the day before.

The Jordan slaying prompted the imposition of extraordinary security measures at Lake Clifton last week. Administrators hope the restrictions, the strictest in Baltimore and perhaps the state, will stop students from bringing guns into school.

They are also meant to keep outsiders off campus and to ensure that Lake Clifton students stay in class and out of trouble.

Among the recent changes:

*Students are now required to wear identification badges and submit to random searches of personal property.

*Students can go to their lockers only twice a day -- when they arrive in the morning and when they leave in the afternoon.

*Jobe and two school security officers conduct regular "sweeps" of hallways looking for students cutting classes. Parent volunteers patrol the hallways and grounds.

*Unannounced home-room periods are occasionally called at the end of the day to take attendance. Students 16 and older caught cutting classes or leaving school will be expelled, Jobe said.

*All but one of the school's approximately 80 outside doors have been locked, allowing administrators to scrutinize students' comings and goings.

Administrators are also considering installing a metal detector at the school's main entrance.

"We can't keep a handgun out of school if somebody's intent on bringing one in," Jobe said, "but we want to make it as difficult as possible.

"We had to do something; we had to respond. We want our kids to know we care about them."

Jobe is concerned that the two slayings at Lake Clifton have given his school an undeserved reputation for violence. The vast majority of his students do not have disciplinary problems, he said.

Similar violent incidents have occurred recently in schools in Prince George's County. Last month, a 17-year-old Clinton youth was stabbed to death, allegedly by another student with whom he had feuded, as he was boarding a bus home from Surrattsville High School.

In October, a 17-year-old Forestville High student was shot and killed in the school parking lot. Three youths, none of them students there, have been charged in that slaying.

And this month, the principal at Kenilworth Elementary School in Bowie found a loaded handgun in the desk of a fifth grader. The boy had been arrested in January for possessing a gun and released to his parents' custody.

Officials here have been grappling with the problem of guns in schools for several years, and despite continuing incidents of in-school violence, some of their efforts have been effective.

A year and a half ago, the Baltimore school system adopted a policy of expelling all students caught with guns. The 122 gun-related incidents in city schools in 1983-84 dropped to 66 last year. As of the end of December this school year, the number of incidents had dropped to 23.

A spokesman for the schools' security force said about one-third of the gun-related incidents on school grounds involve possession; a third are assaults, and a third are robberies. Only about half of the persons involved in the incidents are students, he said.

Law enforcement authorities and community leaders have launched efforts in the last year to stop teen-age homicides in Baltimore. Police and prosecutors have gone into schools to urge students to report youths carrying handguns.

A group called Coalition to Stop the Killing has held marches and vigils and is trying to bring student leaders and young black professionals into poor areas of the city to serve as role models for youths who see crime as a way out of poverty.

The violence at his school, Jobe believes, is linked to much larger social problems.

"It's due to expectations of students, lack of parental control, the availability of guns, drugs, teen-age pregnancy, unemployment," he said.

"I think all of us are going to have to get involved in getting kids into a more controllable situation. It's not an issue the schools can address alone."