The leader of the Haitian gang suspected of kidnapping 17 members of a missionary group from the United States has threatened to kill the hostages if his demands are not met.

Wilson Joseph, leader of the 400 Mawozo gang, issued the ultimatum in a video posted on social media on Thursday.

"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,” Joseph said in the video.

Earlier this week, Haitian officials said the gang is demanding $1m in ransom per person to free the hostages.

Speaking in front of the coffins of gang members apparently killed by the police, Joseph threatened Haiti’s Prime Minister Ariel Henry and the chief of National Police Leon Charles in the video,

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

Al Jazeera correspondent Manuel Rapalo said protests in the capital Port-au-Prince against the deteriorating security situation in Haiti continued for the fifth day on Thursday.

Haitian workers went on a general strike on October 18 to protest worsening insecurity and gang violence after the abduction of the Christian missionaries.

"The concern now, especially after this video was published, is that tensions are going to continue to escalate; there’s fear that violence could worsen on the streets,” Rapalo said.

The hostages were abducted after leaving an orphanage outside Port-au-Prince on October 16. Sixteen of the abductees are Americans and one is Canadian. Five of them are children, including an eight-month-old infant.

Christian Aid Ministries, the Ohio-based missionary group whose members were kidnapped, called for a day of fasting and prayers for the hostages on Thursday, urging people to pray for the abductees as well as the kidnappers.

"Pray for the kidnappers, that they would experience the love of Jesus and turn to him, and we see that as their ultimate need,” said Weston Showalter, a spokesperson for the group.

"We also ask for prayer for government leaders and authorities as they relate to the case and work toward the release of the hostages.”

Reporting from Millersburg, Ohio, Al Jazeera’s John Hendren, said the kidnappings have been "stressful” for people associated with the missionary group.

"The people we’ve talked to have all expressed deep concern for those missionaries, particularly after the threat that was given by the leader of that kidnapping group,” Hendren said.

One of the poorest countries in the world, Haiti has been suffering from periodic natural disasters, gang violence and a longstanding political crisis made worse by the assassination of President Jovenel Moise in July.

The country has seen a surge in kidnappings during the past weeks. Center for Analysis and Research in Human Rights (CARDH), a Haitian NGO, said on Wednesday that at least 119 people were kidnapped by criminal gangs in Haiti during the first half of October, following 117 cases in September.

"Citizens do not trust the Haitian national police and this poses a problem because we cannot have an efficient police force if the population does not collaborate,” Gedeon Jean, CARDH director, told AFP earlier this week.

The US government has promised to work with Haitian authorities to free the American hostages.

"We have in the administration been relentlessly focused on this, including sending a team to Haiti from the State Department; working very closely with the FBI, which is the lead in these kinds of matters; in constant communication with the Haitian National Police, the church that the missionaries belong to, as well as to the Haitian Government,”  Secretary of State Antony Blinken said on Tuesday.

"And we will do everything that we can to help resolve the situation.”