The team said in a statement that alarms were pulled at approximately 5:40 a.m. PT -- only on the floors of the hotel that Panthers players were staying on, which backup quarterback Derek Anderson confirmed in a tweet Sunday.
Just happened to be our floors only.. Guess that's just by chance lol— Derek Anderson (@DAnderson314) October 18, 2015
"Obviously, this is an issue that directly affects our club. We will let the hotel and the league investigate," Panthers spokesman Steven Drummond said.
The team said it got the all-clear to return to its rooms at approximately 6 a.m. PT.
Several other players also tweeted their unhappiness at the unexpected interruption in their sleep.
Who pulled the fire alarm...😒 pic.twitter.com/n7Wmv5oShD— Graham Gano (@GrahamGano) October 18, 2015
Fire alarm at 530am 👀😴😴😴😴😴— Jonathan Stewart (@Jonathanstewar1) October 18, 2015
Whoever pulled the fire alarm on the 16th floor....not cool. 👎🏿👎🏿— Charles Tillman (@peanuttillman) October 18, 2015
Outside linebacker Shaq Thompson said after the game it had to be a purposeful disruption of the team's rest.
"It had to be an inside job," he said. "There's no way it could hit all three floors. There's just no way. It was weird."
Cornerback Josh Norman agreed.
"When floors 15, 16 and 17 was the only ones that were going off ... c'mon," he said. "And we were the only ones outside. I don't think that's [too difficult] to piece together."
Quarterback Cam Newton said he "didn't budge" out of his bed.
"I stayed in my room," he said. "I didn't know what time it was. I figured if it was something important Coach [Mike] Shula would call me. I'm a hard sleeper. I got a pretty good sleep last night."
Tight end Greg Olsen said players were downstairs for a short time before being allowed back to their rooms.
"We stood outside on the sidewalk for a little bit, then they let us come in the lobby," he said. "Then, 10 to 15 minutes [later] we went back up. I was probably back in the bed at 10 'til six. Relaxed a little bit.
"The hardest part was walking down 16 flights of stairs," Olsen said. "The alarm got me, but then the guy's voice over the loudspeaker was somewhat concerning. Then, a bunch of us peeked our head out [into the hall]. The first guy I saw was [receiver Ted Ginn Jr.]. We kind of looked at each other like, 'I guess we should go down.'"
The manager at the hotel told ESPN's Michele Steele that an "investigation is still ongoing" that aims to determine the cause of the incident.
The Panthers (5-0) came into Sunday's game undefeated with their only loss in the past 10 games coming against the Seahawks at Seattle in the playoffs last season. With its 5-0 start, Carolina has surpassed the previous team record of eight straight regular-season wins that was set in 2013.
ESPN.com Panthers reporter David Newton contributed to this report.