(CN) — Some immigrants held in federal detention facilities could be freed amid the outbreak of Covid-19 in immigration jails across the country as federal officials announced on Tuesday they are “reviewing cases” of people vulnerable to the virus.

U.S. Immigration and Customs Enforcement says it has identified 600 “vulnerable” detainees, including people who are over 60 years old and women who are pregnant, that could be released from federal custody. Following Centers for Disease Control and Prevention guidance and the advice of medical professionals, “ICE may place individuals in a number of alternatives to detention options,” the agency said in a statement.

“Decisions to release individuals in ICE custody occur every day on a case-by-case basis,” it added.

News that the agency instructed field offices to consider the release of certain detainees follows reports of confirmed Covid-19 cases in detention facilities across the nation and numerous lawsuits filed by advocacy groups who say these facilities have historically lacked adequate medical care for detainees and unreported security incidents. At one facility, a watchdog report found nooses in detainees’ cells.

Detainees at a U.S. Immigration and Customs Enforcement detention facility in Tacoma, Wash., in 2019. (AP Photo/Ted S. Warren)

News of the possible release of detainees was first reported by BuzzFeed, which cited an email from an agency official sent to congressional staffers about the possibility of the case-by-case review.

Criminal backgrounds and immigration history will also be considered when those cases are reviewed and, as of March 30, the agency had identified 600 detainees as vulnerable and released 160 individuals.

As of Tuesday, ICE reported six additional cases of people held in federal detention facilities who tested positive for Covid-19, including a 24-year-old Guatemalan national at La Palma Correctional Center in Arizona, a 25-year-old Indian national at LaSalle Correctional Center in Louisiana, a 67-year-old Cuban national at St. Clair County Jail in Michigan, a 29-year-old Brazilian national at Essex County Jail in New Jersey and a 29-year-old Bangladeshi national at Pike County Correctional Center in Pennsylvania.

The agency also reports that a 29-year-old Mexican national at a Miami-area hospital earlier this month who was transferred to a detention facility. In total, at least 20 detainees have tested positive for Covid-19, according to ICE.

The American Civil Liberties Union reports that it has filed lawsuits in 13 states demanding ICE release clients who are at high risk due to the coronavirus and so far 30 of the nonprofit’s clients have been released.

“ICE is finally acknowledging that what we have been fighting for in the courts is true: Immigrant detention is a death sentence for people who are at high risk due to age or underlying medical conditions,” ACLU senior staff attorney Eunice Cho said in a statement. “Of course, public health experts have been clear that we need to see dramatic reductions in the 35,000 people who are detained – many more than 600 must be released to meaningfully mitigate the spread of COVID-19 and avoid a humanitarian crisis.”