TACOMA, Wash. - A man accused of going on a shooting spree at a crowded shopping mall sent a text message to his ex-girlfriend minutes before the rampage saying he was about to show the world his anger, the woman said. Six people were injured, one critically, in Sunday's attack. Dominick Sergio Maldonado, 20, surrendered about four hours after he ducked into a music store and took three hostages, all of whom were released unharmed, authorities said. Tiffany Robison, Maldonado's former girlfriend, said in an interview broadcast Monday on ABC's "Good Morning America" that he sent her a text message shortly before noon reading: "Today is the day that the world will know my anger." She said he also contacted her during the standoff. "He called me and said he just shot up the Tacoma Mall and he's in the Sam Goody taking hostages," Robison said. Bret Strickler, who said he was Maldonado's best friend, told the Seattle Post-Intelligencer he received a similar text message while Maldonado was holding the hostages. Authorities said they began getting calls about 12:15 p.m. that shots had been fired inside the mall. The first caller said a gunman "was in the mall, walking along, firing," Tacoma police spokesman Mark Fulghum said. State Patrol and police units from nearby agencies clustered around an entrance at the south end. Inside, Stacy Wilson, 29, heard a popping noise and turned around. "I saw the gunman randomly shooting. I ran with a group of women to Victoria's Secret," Wilson said. She said they crouched behind a wall in the store, and when the shooting stopped, an employee ran out and closed a security gate at the front. Wilson said she heard 15 to 20 shots. "He was walking backward and shooting. I couldn't see his face," she said. "Everyone was running and screaming." A man told KING-TV the gunman was smiling as he fired an assault rifle in bursts of four to five shots. A woman who said she made eye contact with the "very clean-cut" gunman before he opened fire told Northwest Cable News, "When I heard the shooting I thought, 'This is a joke. ... I couldn't believe this was actually happening, that someone would do this." Court records show Maldonado has an extensive juvenile criminal history dating back to 1998. He has been convicted of burglary, theft and possession of burglary tools and he had been ordered not to possess any weapons, the Times reported. "I think honestly that he just wanted attention. It's the sick attention that he wanted," Robison told ABC. She said they broke up months earlier "because of an issue with a drug." While the suspect was in the music store, employee Joe Hudson was able to pick up a phone call from The Associated Press and say he and others had been taken hostage. He said little more but could be heard telling others that he was talking to the AP. Susan Serveau said she also called her daughter, Kathy Riggans, 24, a manager at Sam Goody, as soon as she heard about the shooting. "She was upset and scared. She was crying," Serveau said, standing in a parking lot near the mall. "All she would say was that she was OK." Serveau cried with relief when her daughter, store manager Kathy Riggans, and the other hostages were released unharmed. "I'm going to give her a big hug and tell her how much we love her," Serveau said. "I'm just happy she's OK. It's been nerve-racking, very nerve-racking." Six people were taken to hospitals, most with minor injuries, according to Tacoma Fire Department Deputy Chief Jon Lendosky. One person was in critical condition at Tacoma General Hospital, spokesman Todd Kelley said. Maldonado was booked into the Pierce County Jail on six counts of assault and three counts of kidnapping, according to jail records. He was being held on $450,000 bail.