More than 240 people across Southern California were taken into federal custody last week, authorities said Monday. The Immigration and Customs Enforcement detained 244 immigrants who were in the country illegally, most of them with at least one felony conviction on their records, a press release said. It was the country’s most successful four-day sweep, Immigration and Customs Enforcement said.

The sweep was concluded Thursday by the agency’s National Fugitive Operations program, which is responsible for finding at-large criminals for deportation. All of the 244 foreign nationals taken into custody during the sweep had prior criminal convictions, with 56 percent having felony convictions for serious or violent offenses including sex crimes, weapons charges and drug violations. Among those taken into custody, 191 were from Mexico, but there were representatives from 21 countries including Peru, Thailand, France and Ghana. The arrests occurred in six Southern California counties, with the largest number coming from Los Angeles County. 

In the past, locating and deporting immigrants who had been convicted of crimes was much easier, the Los Angeles Times reported. Immigration and Customs Enforcement would contact local jails and ask the inmates be held there until they could be picked up, but last year a federal judge ruled the detainer requests were illegal. Now, officials said they have to rely on manhunts, which are expensive and dangerous. Data from the Immigration and Customs Enforcement found of the 27,000 people arrested by the agency nationwide last fiscal year, roughly 78 percent had criminal convictions.

People arrested during the sweep who have pending deportation orders or who have returned to the U.S. illegally after being deported are subject to immediate removal from the country, the Los Angeles Daily News reported. The remaining individuals are scheduled to appear before an immigration judge.