Israeli strikes killed at least 28 Palestinians in southern Gaza and troops raided one of the last functioning hospitals in the north as the country pressed ahead with its offensive against Hamas on Tuesday with renewed backing from the United States, despite rising international alarm.

A strike on a home in Rafah where displaced people were sheltering killed at least 25 people, including women and children, and another killed at least three people, according to Associated Press journalists who saw the bodies arrive at two local hospitals early Tuesday.