– Greater Manchester Police has released CCTV images of suicide bomber Salman Abedi from the night of the deadly attack at Manchester Arena.

In a statement, police said 14 locations are still being searched in connection with the investigation and at least 13 people have been arrested.

“The investigation is making good progress and we know one of the last places Abedi went was a city centre flat and from there he left to make his way to the Manchester Arena,” Greater Manchester Police said.

Twenty-two people were killed in the attack on Monday night, including seven children.

On Saturday morning, British Prime Minister Theresa May announced the U.K. threat level was lowered from critical to severe. According to BBC, May said significant police activity in the last 24 hours led to the decision to reduce the level.

Greater Manchester Police said around 1,000 people are involved in the investigation and hundreds of officers are involved in security around Greater Manchester.

“This is still a live investigation which is not slowing down,” police said. “Our priorities are to understand the run up to this terrible event and to understand if more people were involved in planning this attack.”