The Kansas City Chiefs held their first practice of training camp with the entire roster on the field together Thursday afternoon on the campus of Missouri Western State University.

Here are five things that you need to know:

1.    Perfect weather, plenty of fans, and lots of autographs

There are a lot of different reasons that people come to training camp.

Some people want to see the start of the new season—the foundation being built of a team with high expectations and loaded with arguably the league's most talented young roster.

After all, this is where it all begins.

There are also those who come to camp because they know it's the closest they'll be able to get to the players throughout the year.

If you're looking for a photo with Eric Berry or an autograph from Patrick Mahomes, your best shot at both of those things is at training camp.

There are plenty of other reasons to make the trip to St. Joseph, Missouri, as well, but for the thousands of fans who made the trip out Thursday afternoon—they were able to witness the very beginning of a three-week journey that will set the stage for what this team could become moving forward this season.

It was the first day and the weather was perfect. The crowd was into it, and all of the players showed their appreciation for the fans who came out by signing autographs and meeting with fans well after the practice was over.

It's the first observation from the first practice because it's easily the most important.

What took place on the field Thursday was what's called a 10-10-10 practice. The first, second, and third-teams got 10 reps each before the next group jumped in there. It's a lighter practice and not as physically demanding as some of the others.

The reason for that is that the players had their conditioning test this morning, and so they were, rightfully, tired.

And while that's kind of the name-of-the-game up at camp—working through fatigue, it made the workout Thursday, which lasted just shy of two hours and was with the guys in shorts and helmets, tough to take any real takeaways from what was happening on the field.

With all that said, here are a few things that stood out:

2.    Mitch Morse and Cam Erving are rotating at center

Coach Reid was asked after practice about the fact that both Cam Erving and Mitch Morse were rotating with the first-team offense at center.

Erving, who got the nod at the beginning of practice, had taken those key reps throughout the offseason while Morse continued working his way back from a foot injury that cost him most of last season.

Reid said that Morse, who has started every game of his career at center whenever he's been healthy, would be brought along slowly, and therefore some reps would be split among them.

In any case, it's a key storyline to watch throughout camp considering regardless of who it is at center—they're working with a new quarterback in Patrick Mahomes.

3.    Patrick Mahomes threw one deep to Sammy Watkins

There were a lot of fans who came out and simply wanted to see Mahomes—the uber-talented second-year quarterback—toss a few deep down the field, and there was one particular toss from Mahomes to Sammy Watkins that was exactly what they wanted.

Mahomes uncorked one deep down the field to Watkins for what would have been a 60-plus-yard touchdown. It was a perfectly timed throw-and-catch on a deep-post that saw Watkins get over the top of the defense and catch the ball in stride.

4. Steve Nelson snagged the first interception of camp

There might not be a player on the Chiefs' roster who is currently carrying a bigger chip on his shoulder than cornerback Steve Nelson, who hasn't been shy about his goals for this season.

He's put it on social media, he's discussed it with the media, and he's generally accepting of the role and responsibility of being the only guy on the roster right now who was in the Top 5 of snaps played at the position for the Chiefs last year.

It's a whole new group, and Nelson is ready to step up and lead.

"Intensity and accountability," veteran All-Pro safety Eric Berry said of Nelson earlier this offseason, adding that Nelson 'never does' get the credit he deserves. "What he brings to the practice field and workouts, it's crazy. He gets feisty. I call him, 'Little Scrappy.' He's a scrappy little dude. He can get intense.

"He demands the best out of himself and the best out of his teammates. I think that's cool."

Nelson got off to a good start Thursday afternoon by snagging the first interception of camp—a deflected pass intended for tight end Alex Ellis, and Nelson took it back the other way for the Chiefs' defense.

At this rate, Nelson will have 15 interceptions at training camp, which would be an all-time record. True story.

5. Reggie Ragland placed on NFI; Three other guys don't practice

There was one piece of injury news that came out of Thursday's practice, and it wasn't anyone getting injured on the field.

Reid said after practice that starting inside linebacker Reggie Ragland has been placed on the NFI list.

"His knee puffed up on the flight here, it's that simple," Reid explained. "He's in great shape and we're just going to let that calm down. It's a precautionary measure and I don't think it's anything to [worry about]."

Reid didn't seem concerned when asked about the injury further.

"He's been on a couple long trips," Reid added. "He had to go to Mexico and do that for our Mexico trip, then he flew back [home] and flew here. Those things happen. I don't think this is an alarming thing. I'm not worried about it."

Ragland suffered a torn ACL two years ago that cost him his entire rookie season. He was brought along slowly last year and ended up starting the final 10 games of the season.

**Leadership Personified: Reggie Ragland’s Remarkable Journey Has Built Him for This Moment**

The other three players who didn't participate on Thursday were rookie safety Armani Watts (ankle), receiver Josh Crockett (sick), and cornerback Ashton Lampkin (knee).