"We want to find Maddox. We want to find him today," Gastonia Police Chief Robert Helton said at a news conference Wednesday. "We want to find him right now."
Police say the 6-year-old has autism and is nonverbal.
Chief Helton said that while a lot of people who were at Rankin Lake Park that day have called police, there are many who have not.
RELATED: 'Everybody looks at you as a monster' Father of NC boy speaks for the first time since Maddox Ritch went missing
On Thursday, an elite FBI dive team with specialized equipment will assist in the search of Rankin Lake.
"They have specialized sonar equipment," Former FBI Assistant Director Chris Swecker told WSOC. "They would grid out a search even though it's a lake bottom."
Officials said they would like to speak with everyone who was at the park on Saturday.
Working non-stop to #FindMaddox. Searchers surging at Rankin Lake Park in Gastonia. Call the tip line! We desperately need to hear from EVERYONE in the park on Saturday. 704-869-1075. pic.twitter.com/cg8J0wPKaW— FBI Charlotte (@FBICharlotte) September 27, 2018
Chief Helton also said there was a man wearing a camouflage hat, loading a silver kayak into a white pickup truck, who they would like to talk to.
There are now 330 people searching and authorities are following up on 250 leads.
Maddox's father, Ian, also spoke at the news conference. He said that his son loves to run but usually stops before he gets too far away.
WATCH: Father speaks at news conference
That's not what happened Saturday, though. He said Maddox saw a jogger pass by, which made him want to run too. He got too far ahead and Ian said he was unable to catch up.
"I'm not eating. I'm not sleeping," Ian Ritch said. "I'm just worried about getting my little boy back. I thought after the first night, he would be fine. I just want my little boy back home. I want to know he's safe. I want to give him a big hug as soon as I see him, I just want to know he's safe."
The father said he is a diabetic and because he has neuropathy in his feet, he has trouble running.
"He likes running," Ritch said. "I couldn't catch up with him. I feel guilt for letting him get so far ahead of me before I started running after him."
Reporters asked Ian why police were not called until an hour after Maddox went missing. He said he thought that between his friend and the park rangers, they would have been able to find the boy on their own.
RELATED: FBI uses parents' voices in search for Maddox Ritch, the missing 6-year-old boy with autism in North Carolina park
When Maddox still hadn't turned up an hour later, a park employee called 911.
He was last seen Saturday around 1:30 p.m.
A candlelight vigil was held for the boy Wednesday night.
The FBI is offering a $10,000 reward for information that leads to the location of the boy.
Anyone with information is asked to call the tip line at (704) 869-1075.