HOUSTON — Houston Police Chief Art Acevedo says inaction on gun control has “failed thousands of families” and is urging people to take a stand against gun violence following the mass shooting in Las Vegas a week ago.

Acevedo tweeted Sunday: “When will we stand up and say enough?”

He says he has “spoken out against gun violence,” and that everyone else should too, asking: “If not now, then when?”

In a follow-up tweet, the chief, who has long advocated stricter gun control, chastised those who say it’s too soon after the Las Vegas shootings to open such a discussion. Instead, Acevedo says it’s too late.

He says: “We’ve failed thousands of families, of all ages, races and faith. Stand up and be heard.”