If waking up Monday to news of the worst mass shooting in U.S. history left you feeling angry or devastated, there’s a solution: take action.

The Las Vegas Metropolitan Police Department said in a statement saying that residents should donate blood to the more than 400 people wounded when 64-year-old Stephen Paddock opened fire from his hotel room late Sunday.

Specifically, United Blood Services is set to start taking donations at 7 a.m. local time at 6930 West Charleston Boulevard in Las Vegas or 601 Whitney Ranch Drive in Henderson. The University Medical Center of Southern Nevada is also preparing to launch a blood drive Monday at the Delta Point Building, though the exact time of that event has not yet been announced.