Micah Flanaburg was fishing with his father-in-law, Ross Webber, when an underwater attacker rocked his kayak; it was a great white shark.

CBS San Francisco reported Flanabug and Webber were fishing Tuesday evening just outside an area frequented by swimmers and surfers when the shark grabbed ahold of the kayak.

"As I'm looking back, trying to figure out what the hell is going on, he came up straight underneath me...and the whole kayak was probably lifted out of the water," Flanaburg said. "And as it grabbed a hold of me, it started shaking the boat front to back. And it wouldn't let go."

Flanaburg said the shark bit into the kayak, circled it and swam away, lasting approximately 10 seconds.

"Probably the scariest part was when it let go, 'cause it swam back around and I thought he was going to come and take another bite, right where my legs were," Flanaburg said.

Webber said the attack occurred "not too far from shore" and was close to where people would regularly swim and surf.

Flanaburg estimated the shark to be 12 feet long and said it lifted the kayak off the water.

"I was pretty much helpless, just hanging on for dear life," he said. "The whole kayak lifted up from below me, and the great white shark grabbed the whole front of the kayak and was shaking it violently."

The two men returned to shore unharmed and alerted the police of the incident.

According to the International Shark Attack File, shark attacks have been on a small upward trend. In 2011, 29 attacks were reported and, in 2012, 53 were reported.

Flanaburg told NBC News he identified the shark immediately and said it was like something straight from the Discovery channel.

"[The] Shark's eyes were rolled up in the back of his head," he said. "I saw his gums and all his fangs bared. His whole head was halfway out of the water."

Authorities are continuing to monitor the area and have posted warnings for all beachgoers.