Police in Minneapolis, Minnesota, have arrested 20 people in connection with a string of violent robberies that have rocked the city’s downtown district.

Authorities have already charged 18 of those arrested, ages ranging from 15 to 27, according to WCCO. Multiple videos show a group of young men surrounding would-be victims and stealing victims’ wallets and other valuables, often violently.

Robberies increased more than 50% from 2018 to 2019. From Jan. 1 to Aug. 26 last year, 156 robberies took place. In the same time frame in 2019, victims reported 240 robberies.

During a three-week stretch in August, 48 robberies were reported. Nearly half of those, 23, took place in one week.

Most of the robberies take place between 10 p.m. and 3 a.m., though robbers have targeted victims in daylight, and security camera footage shows the crimes taking place. In one incident, more than a dozen people surround a man, beat him, and leave him unconscious after stealing his phone.

Read the charge documents below: