“Let’s go Pitt,” then, “F— the cops,” the mob chanted, caught on a YouTube video. Pitt… “Let’s go Pitt,” then, “F— the cops,” the mob chanted, caught on a YouTube video. Pitt students and their friends ran in front of the camera, danced around two blazing fires in the middle of the street and screamed in the background.

The crowd overflowed porches and balconies, spread across the front yards and congested traffic on Semple Street in the early afternoon April 18.

When the sky turned dark over the partying Oakland students, SempleFest turned into a riot. Ultimately, the city and Pitt police and the fire department extinguished both the partying and the fires.

Police cited or arrested 20 party-goers celebrating the last weekend of Pitt’s school year. But more than 1,000 young revelers that day and night took over the 300 block of Semple Street, stretching from Louisa Street and spilling onto Bates Street in Central Oakland.

All 600 commemorative T-shirts the organizers made for the event sold by 3 p.m. Friday. Not only were the ‘Fest fiends dropping $10 per shirt, they also gave $5 or $10 per plastic red or yellow Solo cup, their tickets to the many kegs filled and refilled with beer throughout the day.

Forty to 50 residents from about 10 houses along Semple Street worked together to plan the event, giving the student residents of Oakland their annual chance to celebrate the end of a school year with their classmates.

“Nothing really bad was happening, people were hanging out, it was a beautiful day, they were saying goodbye to people from their classes,” said Patrick Johnson, who helped plan the third annual celebration and whose housemates at 355 Semple St. opened their door for the celebration.

Police watched the situation in the afternoon, when the party remained relaxed and “joyous,” said Johnson.

“There was a turning point in the night when it actually got dark. A lot of people came in, guys were ripping off their shirts, trying to start fires, getting rowdy,” he said.

By the end of the night, police had reported seven open container offenses, six underage drinking arrests, six disorderly conduct violations and one arrest each for harassment and for possession of narcotics at SempleFest. At a quarter past 2 a.m., police cited one student for public intoxication.

The citations began early Friday afternoon, some reported no more than a half an hour apart, and stretched until early Saturday morning when officers cleared the scene at 2:53 a.m, the police reports said.

At any college block party, the presence of alcohol and underage attendees is inevitable.

From Pitt law professor John Burkoff’s perspective, it’s impossible for police to enforce laws completely in the types of situation like SempleFest.

“In American law, a police officer never has to make an arrest. If he sees something illegal, he has discretion,” he said. “Police officers can and they do choose to arrest this person and not this person.”

When house parties turn into mobs in the street, though, officers might arrest the more visible violators in the crowd to set an example for the onlookers, he added.

Pitt police chief Tim Delaney added to Burkoff’s theory.

“It’s a case-to-case basis in enforcing liquor violations,” said Delaney. The Pitt police pursue citations if they are called in for a disruption, harassment or a parking problem, among other things, he said.

Once the Pitt police and the party-goers had wrapped up SempleFest, the residents of the street faced not only Dumpsters that had been lit on fire, but also dozens of bags of garbage, which Johnson said they cleaned up that night into the morning.

The morning after, the Oakland Planning and Development Corp., with volunteer groups and the Oakland Community Council to keep the neighborhood’s streets free from harm, barely buzzed with complaints about the college students’ celebration.

“My phone was not ringing with people saying we need to stop this,” said the group’s executive director, David Blenk. “I heard more about the giant snowball in Oakland Square this winter than the SempleFest.”

The OPDC tries “to be proactive with this type of situation,” said Blenk. The group passes out fliers in the neighborhoods, works with student volunteer groups and supports the Oakland Adopt a Block program to keep the streets clean to get students involved in their community.

Most of the residents of the Central Oakland neighborhood, including Semple Street, are students, Blenk said. Ten to 20 percent of those who live in Oakland are permanent residents.