OTTAWA -- Amid questions about why an emergency alert wasn't issued during the hours-long rampage that killed at least 22 in Nova Scotia, the U.S. Consulate in Halifax has confirmed U.S. citizens in the province were sent an additional e-mailed warning.

"The information we used in our emailed alert to U.S. citizens on Sunday was taken from the Nova Scotia RCMP's Twitter account.  It is our protocol - when emergencies occur - to alert U.S. citizens in the area to the situation," Marcia R. Seitz-Ehler, a spokesperson for the U.S. Consulate General in Halifax, told CTV News on Wednesday.

The news of this additional warning for U.S. citizens comes as Canadians in Nova Scotia are pressing officials for answers about why every tool available wasn’t used to warn those living in the area where the violence was ongoing. The RCMP issued warnings about the attacker on Twitter and Facebook, but no emergency alert was sent out.

These alerts, typically used for Amber Alert child abductions, notify an individual's cell phone to ensure they know of an ongoing emergency. They have also been used in some provinces to reinforce the importance of physical distancing amid the COVID-19 pandemic.

"They can use the alert to warn us about COVID and [to] separate, and I believe that's important. But what's more important [is that] there was like 19 lives lost," Nick Beaton, who lost his wife during the violence, told CTV News' Chief Anchor and Senior Editor Lisa LaFlamme on Tuesday.

Prime Minister Justin Trudeau was asked on Wednesday whether the government will be establishing guidelines for active shooting incidents. He said these are "important questions" that will be addressed through the investigation.

"I think there are many families that are grieving incredible losses right now who are asking themselves questions about how things could have been different, how they might've been able to have been warned earlier," Trudeau said.

"We need to make sure we're doing everything we can, every step of the way to protect citizens in any circumstances and I know that those are things that we'll be reflecting on and talking about as a country…in the coming days and weeks."

Nick Beaton and his wife, Kristin, saw information of the rampage on the news on Saturday night. The next morning, they assumed it had ended — and Kristin left the house to go about her day of essential work.

She was later killed.

"We thought he was taken care of. If I had known he was on the loose I would have not let my wife leave the house that day," Nick Beaton told CTV News.

During a Wednesday press conference, RCMP Chief Superintendent Chris Leather said the RCMP was in the process of sending out an alert when the suspect was killed — an hour and a half after the RCMP was asked if it wanted to issue such a broadcast.

"At 10:15 a.m., Nova Scotia Provincial Emergency Management officials contacted the RCMP to offer the use of the public emergency alerting system," Leather said.

"We were in the process of preparing an alert when the gunman was shot and killed by the RCMP."

Speaking on Monday, Leather had defended the use of social media as the RCMP's only warning system during the 12-hour attack.

"We have relied on Twitter, as my colleague said, because of the instantaneous manner that we can communicate. We're aware that we have thousands of followers in Nova Scotia and felt that it was a way, a superior way to communicate this ongoing threat," Leather said.

However, Twitter is not universally used, meaning many Nova Scotians were left in the dark about the horrifying rampage unfolding around them.

"RCMP were tweeting, I don't know, I don't use Twitter and I don't know anyone that does use Twitter," Beaton said.

Nova Scotia Premier Stephen McNeil has also been pressed about why additional efforts weren’t made to keep Nova Scotians informed amid the 12-hour rampage. He said during a Wednesday press conference that the Emergency Management Office (EMO) had asked the RCMP "a number of times" if they wanted to issue an emergency alert.

"The lead agency is the one that has to put the message together. We would not go from what’s happening by Twitter — we would need the lead agency to actually craft the message so that we could put that out, and no message was received even though EMO had reached out a number of times throughout the morning to the RCMP," McNeil said.

Speaking to CTV News Channel on Wednesday, former RCMP inspector Linda Gillis Davidson said she would have directed more communication amid the rampage, had she been involved in the response.

"I think the bottom line here is that if you have a tool in your tool case, you use it," Gillis Davidson said.

With files from CTV's Noah Richardson