U.K. anti-terrorism police arrested two more men in Manchester Wednesday in connection with their investigation of a British man who took Jewish worshippers hostage at a Texas synagogue. 

Four of the six arrested are still in custody.

UK TERROR POLICE ARREST TWO MORE PEOPLE IN TEXAS SYNAGOGUE HOSTAGE PROBE 

British citizen Malik Faisal Akram, 44, took four people hostage at Congregation Beth Israel in Colleyville, Texas, on Jan. 15. The nearly 11-hour standoff ended with the remaining three hostages running out safely and the alleged gunman shot and killed when FBI agents stormed the building. 

He was heard on the synagogue’s Facebook livestream demanding the release of Aafia Siddiqui, also known as "Lady Al Qaeda," a Pakistani national imprisoned in Fort Worth for allegedly trying to kill U.S. troops in Afghanistan.

Two teenagers were detained in South Manchester the day after the Texas incident, but both were later released without charges after three nights in custody. Reports said they were Akram’s sons. 

Two other men were arrested Jan. 20 in Birmingham and Manchester. On Jan. 21, U.K. anti-terrorism officers "were granted an extension of custody to continue to question them further," Greater Manchester Police said at the time. 

Counter Terrorism Policing North West said Wednesday it is "working closely" with U.S. law enforcement.

The FBI has said Akram, from the town of Blackburn in Lancashire, England, was a "terrorist espousing an anti-Semitic world view" and described the incident as "both a hate crime and an act of terrorism." 

Matthew DeSarno, special agent in charge of the FBI Dallas Field Office, said last week the bureau is "following up on a high volume of viable leads," and that Akram "was not known to and who did not have prior contact with U.S. intelligence or law enforcement authorities." 

Akram was, however, reportedly known to British intelligence agency MI5, was previously on the U.K.'s version of a terrorist watch list and had a lengthy criminal record, including a past prison stint for theft and harassment convictions. 

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The FBI confirmed Akram entered the U.S. Dec. 29, landing in New York City before reportedly staying at several Dallas-area homeless shelters. U.S. and U.K. authorities are working to determine if he acted alone or as part of a larger terror cell. 

Akram’s parents emigrated from Pakistan in the 1960s. A 2016 study found the industrial town of Blackburn has one of the lowest level of integration between its Muslim community and the general population.