SAN FRANCISCO (CBS SF) -- Ryan Chamberlain II, a man wanted by the FBI in an explosives investigation, was arrested at Crissy Field Monday evening after a three-day manhunt.
FBI spokesman Peter Lee said that authorities found Chamberlain's car -- a white 2008 Nissan Altima with Texas or California license plates -- near Crissy Field, south of the Golden Gate Bridge.
Morgan Manos, an Uber driver, was taking a break at Crissy Field when authorities caught up with Chamberlain. He noticed the commotion and took out his phone.
"He was asking for help. He saw that I was recording him and said 'Help me,'" Manos said.
Raw Video: Chamberlain Arrest Caught On Video
"They got him on to the ground. They were trying to get him cuffed. They were yelling at him to get one of his arms behind his back. He was complaining that he couldn't, that he was like hurt or stiff or something," Manos said.
San Francisco police officers moved Chamberlain to the patrol car. When officers pulled off his beanie, Manos said he saw a little blood on Chamberlain's face from the struggle.
"There's a manhunt going on, they're looking for him. Why would he be down here watching the bridge and the ocean? So I was just surprised the whole thing happened right where I was," Manos said.
Earlier on Monday, FBI agents and San Francisco Police focused their search in San Francisco's Lower Haight for Chamberlain.
The bartender at The Mad Dog in the Fog bar at 530 Haight Street told KPIX 5 that FBI agents were in the bar earlier Monday afternoon.
Agents questioned bar staff and informed them Chamberlain was inside the bar around 2 p.m. and got cash out of the ATM. The bartender said that the agents told her that they believed Chamberlain might be at an establishment nearby drinking.
The business owner next door, Devon Chulick, owner of DSF Clothing, told KPIX 5 that FBI agents also asked him if he had seen Chamberlain. Chulick said an agent also informed him that Chamberlain used the ATM at The Mad Dog in the Fog.
FBI agents and SFPD officers talked to possible witnesses and surveyed the area.
Lee said earlier, "We take every lead very seriously. When there is a sighting, we will deploy agents and police officers to that area. We're running down every lead."
Authorities said Chamberlain disappeared before FBI agents found explosives during a raid of his apartment at Polk Street and Van Ness Avenue over the weekend.
Before he disappeared, Chamberlain posted a manifesto about his battles with depression. The note chronicled relationship, financial and emotional troubles he had dealt with in recent years, referring to them as the "dark times."
On Monday morning, Chamberlain made posts on social media denying claims from authorities that he is armed and dangerous.
As of Monday, it is unclear why the feds were investigating Chamberlain in the first place. A source close to the investigation told KPIX 5 that there was an arrest in Sacramento County about a month ago and that evidence collected in the course of that investigation led authorities to Chamberlain. No further details on the earlier arrest or what evidence linked the two.
In one of his social media missives on Monday, Chamberlain hinted that he had done something online to attract the attention of the feds. He described it as, "absorbing fuel for morbid fantasies."
Part of Crissy Field was closed off Monday and the bomb squad was called amid concerns about possible explosives in Chamberlain's car. Around 9 p.m., the car was towed after authorities deemed it safe.
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