20-year-old suspect arrested in relation to the Washington mall shooting

20 year old Arcan Cetin has been arrested as a suspect for killing five people at the shopping mall in Washington state.

Washington state police identified the suspect via Twitter as 20-year-old Arcan Cetin of Oak Harbor, Washington.

Recall on the incident:

A gunman opened fire at the cascade mall in Burlington, Washington, on Friday night, killing four females and a male before fleeing.

The first emergency call came in just before 7pm on a busy Friday night at the Cascade Mall: A man with a rifle was shooting at people in the Macy's department store.Authorities announced earlier that the suspect had been apprehended on Saturday evening. 

By the time police arrived moments later, four people were dead, and the shooter was gone, last seen walking towards a local highway.

A fifth victim, a man, died in the early morning hours on Saturday as police finished sweeping the 434,000-square-foot building. 

"This was a senseless act. It was the world knocking on our doorstep, and it came into our little community," Burlington Mayor Steve Sexton said at a news conference on Saturday.

As the small city absorbed the tragic news, critical questions remained, including the shooter's motive.

Surveillance video captured the suspect entering the mall unarmed and then recorded him about 10 minutes later entering the Macy's with a "hunting type" rifle in his hand, Mount Vernon police officer Chris Cammock said.

Authorities did not say how the suspect may have obtained the weapon - whether he retrieved it from outside or picked it up in the mall - but they believe he acted alone.

The weapon was recovered at the scene.

The identities of the victims - four women who ranged in age from a teenager to a senior citizen - were withheld pending autopsies and notification of family.

The identity of the man who was fatally shot was also withheld and may not be released until on Monday.