"Ah! This is the best Jonas day ever!" screamed one tween who cried her way into the exclusive Joe Jonas concert at the new Calvin Klein in Toronto's Fairview Mall. But before the madness began, we took a quick tour of the new space which houses the brand's commercial line for women and men. From workwear basics to on-trend separates, the new shop felt fresh, clean and modern--exactly what CK is known for.

But back to the Jonas. As the man of the hour entered the room, a swarm of buzz followed as fans outside the store spotted the star (even through a wall of mannequins and security!). While he finished off a few interviews before his big performance, Jonas looked cool, calm and collected and decked out in Calvin Klein of course. The performer is no stranger to the label, who now fronts the menswear line and is always spotted at the brand's fashion shows.

As the flood gates opened, a lucky set of about 100 tweens and teens (who scored wristbands that morning) rushed the store landing a front row spot in the retail shop's make-shift concert pit. With smartphones up and ready to snap the star, one girl launched a wave of blistering screams when she said "It's him, Joe Jonas, look!" The deafening sound (trust us, it was deafening) rang louder than a siren and served as a warm welcome for the star who quickly stepped on stage. With two floors of fans outside the store all viewing the concert on a small TV set, Jonas certainly brought down the house and hit after hit.

Watch Now: A clip from Joe Jonas' performance in Toronto