PORT-AU-PRINCE, Haiti — The boss of a notorious Haitian gang accused of kidnapping 17 members of a U.S.-based missionary group last weekend is warning that the hostages will be killed if his demands aren’t met.

“I swear by thunder that if I don’t get what I’m asking for, I will put a bullet in the heads of these Americans,” gang leader Wilson Joseph said in a video posted on social media Thursday.

Officials said early in the week that the 400 Mawozo gang was demanding $1 million for each of those kidnapped, although it wasn’t clear if that included the five children in the group, among them an 8-month-old. Sixteen Americans and one Canadian were abducted, along with their Haitian driver.

Joseph also threatened Prime Minister Ariel Henry and Haiti’s national police chief as he spoke in front of the open coffins that apparently held several members of his gang who were recently killed.

“You guys make me cry. I cry water. But I’m going to make you guys cry blood,” he said.

Later in the day, Henry’s office announced that Leon Charles had resigned as head of Haiti’s National Police and was replaced by Frantz Elbe. The newspaper Le Nouvelliste said Elbe was director of the police departments of the South East and Nippes and previously served as general security coordinator at the National Palace when Jocelerme Privert was provisional president.

“We would like for public peace to be restored, that we return to normal life and that we regain our way to democracy,” Henry said.

There was no immediate comment from Charles or Elbe.

The missionaries who were abducted Saturday during a visit to an orphanage.