Tacoma police spokeswoman Loretta Cool said the man was taken into custody at his home without incident by police and SWAT teams Monday night.
"We believe that this man is a violent sexual predator," Cool said.
The victim was opening the Tender Heart Learning Center about 6:40 a.m. Monday when a man who was waiting outside asked to enroll a child.
The woman felt nervous and texted her mother and husband saying that her instincts told her the man was "creepy." When the woman let the man inside, he attacked her, Cool said.
The mother arrived to find her daughter propped up against a wall inside the daycare and a man inside standing over her with his arms above his head as if he were smashing her with something, investigators said. The man ran off when he saw the mother.
The victim was badly beaten and sexually assaulted, suffering a concussion and possible a broken jaw, police said. She was rushed to a hospital where she is recovering.
Cool said evidence at the scene and detailed descriptions of the suspect by witnesses helped lead detectives to their man.
"This was a very vicious attack on someone," Cool said. "This should never happen in any city and we took it as seriously as the attack was and we went after him."
The suspect, identified by prosecutors as 18-year-old Andrake D. Morris, was booked into jail Monday night for investigation of first-degree rape, robbery and burglary. Bail was set at $1 million.
"As the investigation unfolded yesterday we learned that there were several other cases that he might be involved," Cool said. "And were trying to piece all those other cases together and charge him at one time."
Court documents show Morris is now suspected of sexually assaulting a woman and stealing a laptop from her Tacoma apartment last August, and also of robbing a mother at gunpoint outside a DVD rental box as her 2- and 4-year-old children were present. Prosecutors say both the laptop and the mother's wallet were recovered during Morris' arrest Monday. In addition, the mother picked Morris out of a lineup, prosecutors said.
Investigators also recovered the daycare victim's stolen wedding ring and iPhone at Morris' home, prosecutors said.
Tacoma police will be working with other local police departments to see if their suspect could be responsible for unsolved cases in their area.
"We don't know the extent of all the other cases he's responsible for," Cool said. "We do know that at this point in time, he's responsible for the one that we've booked him on."