Tampa Police have arrested suspected serial killer, still seeking motive.

A Florida police officer who was doing paperwork while sitting in a McDonald's restaurant got a tip led authorities to the suspect accused of killing four people in random shootings over the past two months.

Tampa Police Chief Brian Dugan said during a late-night news conference Tuesday that 24-year-old Howell Emanuel Donaldson walked into the McDonalds and asked a fellow employee to hold a bag with a loaded semiautomatic gun while he went to a nearby business to get a payday loan. The employee consulted with a manager who notified the officer sitting at a table.

When Donaldson returned, police were waiting. He's facing four counts of murder.

Television station WFLA, citing an arrest report, said a search of Donaldson's cellphone found location data storage that indicated three days of recorded times and activities that correspond with the first three shootings on Oct. 9, Oct. 11 and Oct. 19.

The report says Donaldson asked for a lawyer while talking with police.

Still no motive:

Despite having a suspect in custody, Tampa Police Chief Brian Dugan says authorities still don't have a motive for a string of shootings in a neighborhood that killed four people.

Speaking Wednesday morning on ABC's "Good Morning America," Dugan said police will still need help from the public as they try to learn more about 24-year-old Howell Emanuel Donaldson, who was arrested Tuesday and is facing four counts of first-degree murder.

Dugan said he's spoken to Donaldson, who he said was "pretty non-responsive" and subdued. Dugan said Donaldson hasn't admitted to the shootings but did admit to owning a gun he took into a McDonald's shortly before being taken into custody.