The suspects, all boys, told police they were an offshoot of a local gang, although police Capt. Glenn Yorek said Wednesday no official ties to the gang were discovered.
The attacks, sometimes with guns, began in mid-May. Victims, including college students and senior citizens, were targeted in mid-mornings and early evenings.
The group struck 13 times on the bike trail, the Houston Chronicle reported Thursday.
Yorek characterized some of the attacks as "brutal," noting one victim suffered a broken collarbone and broken ribs.
Others were struck on the head and then beaten, he said.
"They thought it was a good summer activity," Yorek said of their motivation. "Some said they needed money to eat or to buy shoes."
The suspects range in age from 10 to 16. The 10-year-old was charged with robbery, the others with organized crime.