LAS VEGAS (AP) — Police searched for two gunmen Wednesday who wounded six young people at a bus stop, an attack that officials believe stemmed from a fight about a girl. Tight security met students entering high schools.

The six were wounded Tuesday shortly after a group of Mojave High School students got off a school bus in a working-class neighborhood in northeastern Las Vegas.

The investigation was focused at Mojave, but security also was increased elsewhere, said Clark County School District Police Lt. Ken Young.

"We've got extra officers at several high schools," Young said.

Police were searching for at least two suspects. The attackers were believed to have fled the scene of the shooting on foot.

Police said they believed the shooting was linked to a fight at Mojave earlier in the day Tuesday. The brawl had been contained by school police, who arrested three male students, all about 16, officials said.

Sheriff Doug Gillespie did not describe how he believed the incidents were connected. The fight at the school did not appear to be gang or race-related, he said.

"At this point, the indicators that we have found ... it's a dispute over a girlfriend," Gillespie told reporters.

Police believe the attackers had been waiting at the bus stop. Gillespie said the shooting did not appear to be random.

Investigators said they found 9 mm and .45-caliber shell casings at the scene. When officers arrived, several witnesses ran away, police said.

Officials said the district had counselors available at the school Wednesday.

"I think the No. 1 question on many people's minds tonight is 'Is it safe to send my kids to school tomorrow?"' Gillespie said Tuesday. "The answer is yes. I am a father, I have a daughter and she will be attending school tomorrow."

Mojave had some 2,300 students last year, about evenly divided among blacks, whites and Hispanics, according to district materials.

The shooting occurred just before 2 p.m., a couple of blocks from two elementary schools. Both were locked down temporarily but reopened in about an hour, district spokesman Michael Rodriguez said.