One survivor of the Siam Paragon shopping mall shooting attack talked about the moment when she faced the 14-year-old shooter while running up an escalator.

She thought she was running to a safe place. Instead, she saw the boy standing on the other end of the escalator. He turned toward her and fired his gun.

Anyapat Thipjirasakul said: "When I saw him, I quickly turned back and ran down the escalator as fast as I could. I heard about four shots. One bullet hit me. I felt pain in my left shoulder but I could not stop.

"I jumped down the escalator. I fell but had to keep running, as I was afraid he would follow me down." She ran toward the entrance gate among the crowd, some of whom were screaming and crying.

"It was horrific. I barely slept during my first night. Whenever I close my eyes, I see him and hear the sound of the gun," she said from hospital.

Anyapat is among the seven people who were shot by the teenager in the afternoon of Oct 3. About 40 bullet shells were found later, mostly scattered on the second and third floors.

Penpiwan Mitthampitak, 30, another survivor, is in a critical condition. She was shot in the head and twice more in the right chest.

Chinese national Li Sha, 30, had two gunshot wounds to her chest, one to her back and another to her right arm. Her condition is stable.

Laotian national Kham Phiou, 28, was shot in her shoulder. The right part of her body is weak and can hardly move.

Thai national Wichen Vijikhaki, 41, was shot in the back. He is now safe. Two victims who died were Chinese national Zhao Jinnan, 34. She died at the scene while Myanmar national Moe Myint died later at hospital.

About 3.15pm on Oct 3, CCTV images show the long-haired boy, wearing a cap, a black hoodie jacket, military pants and black boots, walking with a backpack from his condo to the BTS Skytrain.

He took the train and entered the mall at 3.35pm. He went to a restroom on the M floor, took off his jacket and left his bag on a toilet lid. At 4.10pm, he started shooting, first hitting Ms Kham, a cleaner who was working inside the male restroom.

He started walking from one floor to another. He even took a break to check out Twitter and clicked "like" on news about his crime.

About 4.46 pm, the Special Operations Division received a call asking if the police knew about the shooting at Siam Paragon shopping mall. After the agent said yes, he replied: "I am the shooter."

The call was transferred to an experienced negotiator, Pol Capt Possawat Jongjit.

The policeman asked if there was anything he could do. He also asked for his name and location.

The policeman said the voice on another end said he did not know exactly which floor he was on, but he was sitting on a sofa.

The officer asked if he was at the furniture shop on the third floor. The teenager said yes. The information was passed to another team of police on the ground.

During the conversation, the shooter sometimes asked for his father, said Pol Capt Possawat.

At one point, he said he pointed the gun at himself. He also cried when asked if he would be jailed. "I'm only 14 years old. Will I be sent to jail? Will I be safe?"

The policeman told him to lay down the weapon, which was later identified as a modified blank gun that the shooter bought online.

The officer also told him to leave the shop to meet a team of police waiting outside. The teenager said he couldn't move. He saw many dark shadows outside the shop so asked the police to come in and get him instead.

Pol Capt Thanamorn Nunarod, who led the arrest team, said he saw the teenager talking on the phone while telling him to surrender.

"I told [the teenager] to throw down his weapon, put his hands on the back of his neck and sit on his knees. He seemed to think for a while. Then I had to show him that I had a more powerful weapon." He then surrendered. The shooter was caught at 5.10pm.

The Department of Mental Health said there was not enough information to confirm or deny whether the shooter was mentally ill.

The teenager was also active online and liked playing shooting games. He also practised at shooting ranges, visiting more than dozen times.

On Saturday, the suspect's father attended the funeral of victim Moe Myint in Nonthaburi.

He wanted to apologise to her mother, who travelled from Myanmar for the funeral.

The shooter's father kneeled before the mother and asked for her forgiveness on behalf of his son. The mother pulled the man towards her, as he tried to hand her money in a white envelope, which was refused.

"My daughter is worth more than anything in this world. She can't be exchanged with your money," the mother said to the father.