Shortly after midnight on Jan. 16, a pickup truck pulled up in front of the tiny offices of the Jackson Advocate in a black business district in downtown Jackson. Two men were seen getting out and opening fire with carbine rifles into the storefront of the newspaper, then driving away.

No one was injured; no one was in the offices of the black-owned and edited newspaper at that hour. Editor Charles Tisdale, whose weekly had been the target of a nighttime attack a month earlier, called the latest raid an act of renewed racism.

"I believe the Reagan administration's attitude is drawing racists out of the woodwork," the 56-year-old Tisdale said. And he criticized the pace of the investigation of the shooting by police in Jackson, the capital of Mississippi, a city of 210,000 residents, 45 percent black.

"A very nice young patrolman came out several hours after we reported the shooting, but it was not until two days later after it had been on television that an investigator showed up," he said.

Police Sgt. Chip Tippen, communications officer for the Jackson police department, responded that police were "doing the best we can to solve the case."

Then, last Thursday, one white man, identified by police as a former Ku Klux Klansman, was arrested for shooting into the newspaper office. Twelve hours later a second man, also an ex-Klansman, was arrested. The arrests were made, police said, after an eyewitness to the shooting came forward.

But Tisdale says he doesn't "believe the arrests would have happened, however, if there had not been some pressure from Washington and up East and also from a federal agency."

The FBI office in Jackson, after the arrests, said it had entered the investigation.

Both suspects--identified as Kenneth Painter, 35, formerly of Baltimore, and Larry Howard Walker, 35--had been arrested by police after Klan-style night raids in the Jackson area four years ago, including one against another newspaper, the feisty, now-defunct Capital Reporter. In one of the incidents, both paid fines on misdemeanor charges.

In arresting Walker last week, police confiscated a small arsenal of weapons and ammunition including a seven millimeter machinegun, four Thompson submachineguns, four carbines and 1,500 rounds of ammunition. Both men were later released on $25,000 bond and face a preliminary hearing Tuesday on charges of shooting into an occupied dwelling. Arraignment is expected next week.

In Jackson's white community, meanwhile, there seemed to be little public reaction to the attack on Tisdale's newspaper. Arrests of the two former Klansmen were reported in fairly long news stories in the city's two dailies, the Clarion Ledger and the Jackson Daily News, which initially ignored the story of the shooting incident.

Tisdale's newspaper has been the target of shooting before. The front window had been broken and a shotgun blast fired inside of the small one-story building on Dec. 19.

After that attack, Tisdale said he felt it was likely the result of ill feeling toward the newspaper in the black community as a result of a story about black prostitutes who operate on a street corner a short distance from the newspaper in a black business district of downtown Jackson.

In the wake of the latest attack, however, he said he felt "this sort of thing racist attack is going to continue." He added that "the danger is not what these people tried to do to the newspaper, but police inaction that will inspire more of it."

The Advocate, a journal of news and commentary which claims 25,000 circulation, has been publishing for 45 years and is read almost exclusively in the black community. It had not been targeted by night riders during a wave of Klan activities here in recent years.

The now-defunct Capital Reporter suffered nighttime attacks. On four occasions, its windows were smashed by bricks and gunfire, and in 1978, a cross burning set fire to electrical wiring entering the newspaper's office.