Obama: US 'soul-searching' after teen's killing President Barack Obama answers a reporter's question about the death of Tr...

Obama: US 'soul-searching' after teen's killing

President Barack Obama answers a reporter's question about the death of Trayvon Martin, Friday, March 23, 2012, in the Rose Garden of the White House in Washington. (AP Photo/ Haraz N. Ghanbari)

In this undated family photo, Trayvon Martin poses for a family photo. (AP Photo/HO, Martin Family Photos)

Demonstrators gather to call for justice in the murder of Trayvon Martin at Leimert Park in Los Angeles, March 22, 2012. (REUTERS/Jonathan Alcorn)

US President Barack Obama Friday said the nation needed to do some "soul searching" after the killing of an unarmed black teenager by a neighborhood watch guard, and welcomed an investigation.

"If I had a son he would look like Trayvon," Obama, the country's first African American president, told reporters, as he called the fatal shooting of 17-year-old Trayvon Martin a "tragedy."

Thousands of people late Thursday rallied in the Florida town of Sanford where Martin was shot dead by volunteer neighborhood watch guard George Zimmerman in late February demanding justice.

The mostly African-American crowd demanded the arrest of Zimmerman, who claims he acted in self-defense after a confrontation with the teenager. Zimmerman has been neither detained nor charged with any crime.

An online petition has gathered more than a million signatures following Martin's fatal shooting on February 26, and the Department of Justice has launched an investigation into the events.

"Obviously, this is a tragedy. I can only imagine these parents are going through. And when I think about this boy I think about my own kids," Obama said, addressing reporters in the Rose Garden.

"And I think every parent in America should be able to understand why it's imperative we investigate every aspect of this and everybody pulls together, federal, state and local, to figure out exactly how this tragedy happened."

Sanford Police Chief Bill Lee, who has been criticized for failing to arrest Zimmerman, announced just ahead of Thursday night's rally that he was temporarily leaving his post because he had become a "distraction."

(Agencies)