BALTIMORE, JUNE 11 -- Hundreds of employes of the Baltimore Sun and Evening Sun newspapers, joined by union members from across the city, walked picket lines at the Sun building today to support a strike called last night by the 700-member local of the Newspaper Guild.

Members of five other Sunpapers unions honored the Guild picket line and did not report to work, but the newspapers published despite the strike. Only a single edition of The Evening Sun was published early today, rather than four editions normally published throughout the day.

Readers of the 400,000-cir-culation newspapers found a thinner version of the newspaper arriving on their doorsteps, with delivery delayed by as much as an hour. The last strike at The Sun, in 1978, lasted three days.

Businesses saw their advertisements, planned to increase weekend sales, pulled by management in its effort to produce smaller morning and afternoon editions with roughly half the customary staff.

Television program directors expanded their early evening and nighttime news broadcasts to compensate for what one station official called "the void that's going to be felt in this city."

"We've hired a number of Sun reporters to free lance -- about 13 at last count," said Ross Mason, assistant news director of television station WJZ (Channel 13), an ABC affiliate, which has added an hour to its evening newscast and a half-hour to its 11 p.m. show. "Basically those people will be covering the same beats that they do at the paper. They'll be reporting for us just like they did for them -- just in a different fashion."

Private security officers hired by Sun management and nearly a dozen Baltimore police officers watched the round-the-clock demonstration that appeared as an angry, yet controlled, display of frustration toward failed collective bargaining over wage and health benefits between management and Washington-Baltimore Local 35 of the Newspaper Guild.

A Sun mailroom employe, Richard N. Celmer, 32, of Essex, was arrested about 9:30 a.m. for allegedly jumping on a truck, rented by management to deliver the papers, and breaking a side mirror, police said. The truck was leaving the Sun premises to make a delivery, said city police, who charged Celmer with disorderly conduct.

Publisher Reginald Murphy issued a statement that described the contract proposal made to editorial and commercial employes as "reasonable." He later said in an interview that he believed inexperience on the part of the union's bargaining team could be partly to blame for the contract delay.

"We are not asking for givebacks. We are not asking for changes," said Murphy, who added that he was surprised by the union reaction and its vehemence.

But Guild members said the cause of the strike was a company contract proposal that would hurt them financially. The Sun offered a 1 percent pay raise on Monday and later increased the offer to 4 percent, but would require employes to begin contributing more than $400 a year to health insurance. The company also refused a union proposal to eliminate lower pay levels for employes who work on suburban supplements.

Yesterday's newspapers were published with about half of the regular number of editorial personnel -- editors and nonunion supervisors -- making up the staff, Murphy said. The company has not hired extra drivers, printers or other personnel to produce what Murphy admitted were editions, such as yesterday's Evening Sun, that were half the usual number of pages.

Teamsters Union drivers, along with members of unions representing mailroom personnel, engravers, printers and press operators joined the walkout in the early hours and were later bolstered by picketers from unions such as the United Steelworkers, Communication Workers of America, and United Food and Commercial Workers.

At noontime, the sidewalk outside the red-brick Calvert Street office was filled with placard-carrying employes chanting: "What Do We Want? CONTRACT!"

"The common denominator that united us this time was the 1 percent salary raise proposed on Monday. It was irritating," said Ted Shelsby, a business reporter who has worked at The Sun for 26 years and earns $720 a week. According to Shelsby's calculations, he would have earned $7.50 more a week under the company's original 1 percent proposal but would have had to pay, for the first time, $8.72 a week for health coverage.

Negotiations had not resumed as of late today.

Wednesday night, as the contract expiration approached, union negotiator Sandi Polaski suggested extending the contract for 24 hours. The proposal was soundly rejected by union members who decided in a voice vote that the last-minute package offered by management was unacceptable.

"We all want to work. I want to work. I'm in the middle of a big story and it's no fun to put that all away," said Alice Steinbach, a Sun reporter who won the Pulitzer Prize for feature writing in 1985. Yet Steinbach, like many who have seen previous contract negotiations, said this time management had exhibited an attitude toward its workers that could not be ignored.

"The mood is very different this time. It's very interesting to me . . . . I think people here are much more unified and believe in this more than in 1984," she said.

Maryland Gov. William Donald Schaefer, former mayor of the city, said he was "very unhappy" about the strike and hoped it would be over soon. Schaefer described Murphy as "an excellent publisher" and said he hoped the striking workers "don't get so emotional that they hurt the newspaper."