Just hours before a popular teacher was shot to death near the bar he ran in the small east-metro community of Willernie, many patrons saw him refuse to serve an underage man and later ask the man to leave.

David Frigaard, 46, who taught art at Park High School in the South Washington County School District, was killed early Saturday in Mahtomedi, a few blocks away from Frigaard's Bar.

Bar patron Casey Weber, 22, was among those who said the suspect was angry that Frigaard refused to serve him and apparently waited outside until the bar closed, and "then it happened."

"We believe it was ­somewhat premeditated," Weber said. "It's very surreal."

Police said Sunday that they have a 19-year-old Pine Springs man in custody in Frigaard's death, and that charges are likely to be filed Monday. The Star Tribune generally does not name uncharged suspects.

The Sheriff's Office is investigating with help from the Minnesota Bureau of Criminal Apprehension and the Ramsey County medical examiner's office.

Frigaard's death brought an outpouring of grief from family, friends, patrons and students on Sunday. Many people gathered at Frigaard's bar to toast him and to share memories. Hundreds of people, many of them students and students' parents, posted tributes on the bar's Facebook page and elsewhere on social media.

Many comments spoke to Frigaard's ability to create community. "Dave was a great guy who went above and beyond to help others and he made a lot of strangers friends for life through his establishment," said one Facebook comment. "One of the most unselfish people that I've ever met, shirt-off-his-back type of guy."

Police were called to Hwy. 244 and N. 75th Street in Mahtomedi at 3:17 a.m. Saturday on a report of a shooting. When deputies arrived, they found Frigaard's body lying on the ground about two blocks from the bar. The suspect was arrested later Saturday.

Frigaard was married with children. His family declined to comment on Sunday.

The longtime art teacher for secondary schools across the South Washington School District had been at Park High for about four years, most recently teaching painting, Principal Kerry Timmerman said Sunday.

He also served as an at-risk program teacher and as an adviser for the school's gay-straight student group. And he had been a girls' track coach, assistant football coach, and middle school football and basketball coach over his years with the district, ­Timmerman said.

"Dave was a really caring individual," he said. "He is certainly going to be missed."

Timmerman said the school is preparing to ­provide counseling and grief support for students and staff when they return to school on ­Monday.

'Everyone is in shock'

At Frigaard's, a small, informal, friendly bar, which Weber called his "own Cheers," in reference to the famous TV show, flowers, candles and handwritten notes lined the entrance Sunday afternoon.

"Everyone is in shock," Weber said. "This doesn't happen in a small town. We are not familiar with murder … it's a very scary situation for everyone."

Among all of the stories about Frigaard shared Sunday at the tavern, one about him taking in a student who needed a place to stay may have best shown the kind of person he was, Weber said.

"[Frigaard] took in this student to help him out," Weber said. "He really is a courageous and wonderful guy."

Karen Zamora • 612-673-4647

Twitter: @KarenAnelZamora