Officers have cordoned off a large area of the apartment complex where the girl lives. Neighbors say they saw the teen be taken away in handcuffs and he was supposedly very calm.
The teen is also a resident at the apartment complex where the girl lived. Neighbors say they saw the teen being taken away in handcuffs and was very calm. The teen's mother, however, was in tears and screaming hysterically.
At 9:50 p.m. Monday, Santa Cruz Police Chief Kevin Vogel spoke to the media. He said, "Our detectives discovered the body of a young female inside of a dumpster at the complex located behind me."
Vogel said they have not yet positively identified the body, but they do believe it is Maddy. He added police arrested the teen who was present at the same time police discovered the body at the complex.
RAW VIDEO: Santa Cruz police give update on missing girl case
Police say the dumpster is inside the garage of the apartment complex and it will take hours to process the scene. How the girl died is not yet known.
Neighbors describe the 15-year-old suspect as a nice boy. Neighbor Terrance Keller said, "From what I know, he's very well-spoken and has very kind manners. So like I said, it's just a shocking situation altogether."
Police believe there are no other suspects and say they plan to have another update Tuesday morning.
.@SantaCruzPolice Chief calls this "extraordinarily heartbreaking".— Lilian Kim (@liliankim7) July 28, 2015
.@SantaCruzPolice say they haven't touched body. Don't know how she was killed.— Lilian Kim (@liliankim7) July 28, 2015
15 year old boy, resident of complex, under arrest on suspicion of homicide. #MaddyMiddleton— Lilian Kim (@liliankim7) July 28, 2015
Earlier on Monday, Maddy's mother, Laura Jordan, described her pain as she desperately waited for word on her missing 8-year-old daughter who vanished Sunday night just outside her Santa Cruz home. Police joined by the FBI and neighbors vowed to search every corner and investigate every lead.
Maddy was last seen on surveillance video around 5 p.m. playing outside the Tannery Arts Center on River Street where her mother lives.
"She was riding her brand new scooter, it was a white Razor. She had a black helmet on, she was wearing a purple dress, and she just as happy as can be riding around," Jordan said.
PHOTOS: Police make grim discovery in search for Santa Cruz girl
The CHP issued a statewide, all-points bulletin for all of its officers to be on the lookout for the girl. The search effort has been challenging because of the varied and rugged terrain that stretches from the beach to the summit of the mountains.
Professional search and rescue teams joined local agencies to scour the area, all-terrain vehicles were deployed and air searches were done as well.
"We're all feeling a little helpless at this point," said family friend Emerson Sanderson. "We checked all the tents and homeless camps. A lot of us have been up all night. We've gone as far as Paradise Park and scoured these trails through the river in the dark all night last night."
Earlier Monday, Jordan said she was trying to remain hopeful, "I already fell apart, now I am just in survival mode. I cannot explain how difficult this is. Nobody should have to go through this."
Fellow family friend Joe Mailloux added, "We would have heard her. She's... I don't get this. Nobody gets this. We would have heard. She was just right here. Right here."