MADISON, Wis. – Students from University of Wisconsin-Madison and local high schools staged a walkout Monday morning and marched to the State Capitol, where about 1,500 protested the death of Tony Robinson, 19, who was unarmed when he was shot and killed by a Madison police officer Friday night.

Just before noon, protesters began to enter the Capitol amid chants by organizers, "Be peaceful." It quickly grew into one of the largest Capitol protests since the 2011 rallies against limits on public sector unions, and the share of people of color in this protest easily surpassed that of the previous crowds. The protest remained peaceful.

The high school marchers stopped on Williamson Street near the scene where Robinson was shot. They chanted, "I am Tony Robinson, we are Tony Robinson" and "Whose streets, our streets."

Several hundred marchers from the university arrived at the Capitol first and gathered on the State Street stairs, chanting, "No justice, no peace." Many of them then entered the Capitol and gathered in the rotunda.

Students were asked by organizers to wear all black to mourn the death of Robinson.

Protesters largely had cleared out of the Capitol by 1 p.m. and began marching on streets near the Capitol. Mayor Paul Soglin spoke to the crowd soon afterward.

He urged them to address larger issues like racism and cuts in school funding, but was shouted down by protesters periodically. When he said, "the death of Anthony Robinson," protesters shouted back, "Murder!"

As the protests began, Madison Police Chief Mike Koval issued an apology to the Robinson family in his blog.

"Reconciliation cannot begin without my stating 'I am sorry,' and I don't think I can say this enough. I am sorry. I hope that, with time, Tony's family and friends can search their hearts to render some measure of forgiveness," Koval wrote.

The officer, Matt Kenny, was interviewed Monday by state Division of Criminal Investigation agents as part of an independent investigation.

"Officer Kenny recognizes that the family has suffered a tragic loss regardless of the circumstances," said Jim Palmer, president of the Wisconsin Professional Police Association.

Last year, Robinson pleaded guilty to felony armed robbery and received three years' probation, according to court records. At the time of the complaint, he stood 6-foot-3 and weighed 225 pounds.

Meanwhile, Gov. Scott Walker's office released a statement.

"Our thoughts and prayers are with all those involved. An overwhelming majority of police officers follow procedures and do a good job of protecting and serving the public."