Four other people, including a firefighter burned on his face, were injured in the blaze.
The bodies of four boys and a girl - ages 8 months to 10 years - were found on the second story and were likely family members, officials said.
Authorities said they arrested Zachary Q. Meeks, 27, after he was questioned about the fire that began around 3 a.m. in this community along the Mississippi River and about 90 miles west of Springfield.
Authorities did not release a motive.
Meeks was charged with five counts of first-degree murder, one count of aggravated arson and one count of arson, police said.
Rescuers arrived to find the two-story brick home engulfed in flames, which were shooting through the windows, authorities and neighbors said.
The five bodies were found later.
The surviving victims' identities and details on how they were injured were not released.
One victim was airlifted to a Springfield hospital in critical condition, police Sgt. Doug Schlueter said.
Two others were treated and released from Blessing Hospital, spokeswoman Chris Tysinger said.
A firefighter also was treated for his injuries and released, said Keith Frank, an assistant fire chief.
Police said Meeks was being held in the Adams County Jail.