Relatives of the dead, survivors and shop owners converged outside Nairobi's Westgate Mall on Sunday, lighting candles and laying flowers in memory of those killed a year ago when gunmen stormed the upscale mall.

The attack killed 67 people and left Kenya's capital unsettled for days as militants battled with security forces, and people trapped inside tried to flee the fighting.

A memorial plaque with the names of the victims was also unveiled in a separate ceremony at the Amani Garden memorial site in the Karura Forest on the edge of the city. Families laid flowers for their lost loved ones, sharing memories and tears.

Amu Shah remembered his son Mitul, who was killed in the attack.

"We have been completely shattered; our lives are not as they used to be," Shah said. "He was very lively, very helpful, very cheerful. Anytime anyone needed any help, he was ready to go and help them."

Police doubled patrols in Nairobi, chief David Kimaiyo said Saturday. They increased their presence in public places such as churches, supermarkets and malls after he warned residents to be "extra vigilant" in the coming weeks in anticipation of more attacks.

Al-Shabab militants claimed responsibility for the mall attack saying it was retribution for Kenya's troop presence in Somalia, the group's home base. More recently, Al Qaeda-linked al-Shabab vowed to avenge the death of their leader killed in a U.S. airstrike earlier this month.

While some held memorial ceremonies to commemorate the Westgate attacks, others tried to forget.

Muimi Kiteme, 26, watched a football match Sunday in hopes it could help erase the memories of Sept. 21, 2013.

Kiteme was shot at by the attackers when they arrived at the mall in a car just after midday.

Since it was a weekend, the mall was packed with shoppers and families eating out, he said. Kiteme, who was a driver for a vegetable supply company, was driving out of the malls service entrance into a junction, when a car sped past forcing him to stop, he said.

Four men disembarked from the car and he heard gunshots and his windscreen shattered.

"When we saw the car speed past us and the men with guns, my assistant asked me if they were shooting a movie," Kiteme said.  "When the windscreen shattered he was the first one out of the car. I turned back to talk to him and he was gone. I remained frozen in my seat"

He said he saw a man with a black turban point the gun in his direction and shoot. The bullet missed Kiteme and hit the cushion. Kiteme said he got the chance to escape when the gunman bent over to pick up his black turban which dropped from his head.

"I opened the door and crawled under the car. I could see the gunman's feet as he walked around the car looking for me," he said

"I do not want remember. The things that I saw I want to forget this day. I am grateful to be alive, but I want to forget," he said.

According to the police reconstruction of events, the four gunmen split into two groups. One pair went into the mall's main foot entrance as another went through the vehicle entrance, tossing grenades and spraying bullets at the people in vehicle and in the restaurants.

At a cooking competition on the parking grounds of the mall two attackers killed men, women and children.

The Kenya police force and army have been widely criticized for their response to the attack. It took at least two hours before the Kenya police tactical team went into the mall, leaving security guards and volunteers to fend for those inside.

A new HBO documentary, "Terror at the Mall" by Emmy-nominated director Dan Reed which reviews closed circuit television footage from more than 100 cameras, says by the time Kenya's tactical teams from the military and the police went into the mall, the massacre was over.

Lack of coordination between the military and the police tactical teams led to friendly fire in which one police officer was killed and others wounded.

The police chief on Saturday rejected criticism that the security agencies were disorganized and uncoordinated leading to a slow response to the Westgate Mall attack.

"It was done professionally," he said.

The attack began on a Saturday and the government announced the end of the siege on a Tuesday.

The attackers were eventually killed by a fire caused by a high explosive rounds shot at the mall by the Kenyan military, a police official told The Associated Press on condition of anonymity because he is not authorized to speak with the press about the investigation.

Four men, one of them a relative of the attackers, are facing terrorism related charges in court for the Westgate attack.

A constant drumbeat of grenade and gun attacks blamed on al-Shabab since Kenya sent its troops to Somalia in October 2011 has made some Kenyans call for the troops to be withdrawn.

President Uhuru Kenyatta said in an article published in a local daily newspaper on Sunday that troops will not be withdrawn until Somalia is stabilized.