The hunger strike began Friday at the Northwest Detention Center in Tacoma with hundreds of participants refusing to eat to call for better treatment and an end to deportations.
ICE said Wednesday that four detainees are under medical observation. Officials have declined to comment on the condition of detainees, citing privacy reasons.
Immigrant-rights activist Maru Mora Villalpando says she talked to one detainee who said he wasn't doing well but still planned to continue the hunger strike.
Activists say detainees are seeking better food and treatment, as well as to be released on bond while their cases are heard.