MIAMI (AP) — Police officers found two young children dead after responding to several 911 hang-up calls from an apartment in Miami.

Police spokesperson Michael Vega tells news outlets officers looked inside the apartment and saw the unresponsive children late Tuesday.

Their cause of death will be determined by an autopsy.

He said they appeared to be about 6 and 3 years old.

Vega said officers spoke to a woman at the scene “who appeared to be irate or going through a crisis.” She’s expected to be questioned. Her relationship to the children was unclear.