A United Airlines flight from Anchorage, Alaska heading to Denver, Colorado was diverted to Vancouver, Canada early Saturday morning after a man made threatening messages. Canadian authorities already have the suspect in custody, but no details about the threat are released.

"Flight 1104 departed 11:39 p.m. Friday from Anchorage, Alaska, bound for Denver, but the crew elected to divert the flight after they discovered a threatening message from one of the passengers," Charlie Hobart, a United Airlines spokesman told CNN.

The Boeing 737 plane, with a total 131 passengers and six crew members, landed at the Vancouver International Airport at 4 a.m. The Royal Canadian Mounted Police in Richmond, British Columbia confirmed the emergency landing and subsequent arrest on Twitter.

"We are currently investigating a security concern originating onboard United Airlines Flight UA1104. Their arrival in Canada was not a scheduled stop. Specifics about the exact nature of the security concern are under investigation but we can confirm this appears to be an isolated incident in which security protocols were enacted and the criminal code investigations remains active and ongoing," Corporal Dennis Hwang of the Richmond RCMP in their official website.

The passengers were safely escorted and screened by airport and United Airlines staff before being booked on other flights to resume their travels. A total of five ambulances were called on to the tarmac, but no injuries were recorded and the operations at the Vancouver International Airport run smoothly thereafter.

The FBI is reportedly helping the RCMP in their investigations to determine the correct situation behind the passenger's threat, the nature of it, his background, and most importantly, his motives. As for the remaining passengers, they landed at Denver around 5:30 p.m., Saturday, 12 hours later than their originally scheduled time of arrival, per Inquisitr.

According to a report by CBS Denver, one female passenger sent a text to her daughter about the threat on the plane. "I was really pretty nervous. I was hoping that everyone was okay but I wanted to know why or how somebody got through the security when everything is so elevated already," the daughter, Karen Pomeroy said.

"I think the airline should have the responsibility of either contacting families or making sure that the people are safe and understand what's going on," she added.

United Airlines also made headlines last week after being fined $2.5 million by the US Department of Transportation for violating consumer rules regarding the disabled and its handling of flight delays.