(CNN) -- A 12-year-old Colorado boy suspected in the deaths of his parents and the critical wounding of two siblings appeared Wednesday night in court and was ordered held without bond until his next court appearance, an official said Thursday.
The boy, whose name has not been released, appeared before Judge Kevin Hoyer in Fort Morgan, Colorado. Hoyer ordered the proceedings closed to the public, according to District Attorney Bob Watson of the 13th Judicial District. Hoyer advised the youth of his rights, Watson said.
Formal charges were to be filed by the end of business Friday, Watson said. The next appearance is to be in Burlington, where the shooting occurred, on March 14.
Burlington, a town of fewer than 4,000 residents, is near the Colorado-Kansas border.
On Tuesday night, the boy called 911 to report that at least three people in his house had been shot, police said.
"As a result of the investigation we have conducted so far, we are here this afternoon to announce that the 12-year-old family member who placed the 911 call from the residence has been taken into custody," said Colorado Bureau of Investigation Division Director Steve Johnson, in a prepared statement Wednesday.
"The case has been referred to the district attorney's office for the filing of formal charges," Johnson stated. "There are no other suspects at this time."
Investigators responded to the boy's 911 call around 6:40 p.m. on Tuesday, law enforcement officials said. Upon arriving, they discovered the bodies of the boy's parents, Charles Long, 50, and Marilyn Long, 51.
Officers also found two critically wounded children: a 5-year-old girl and a 9-year-old boy, whom authorities identified as siblings of the boy in custody.
The children, whose names have not been released, were taken to an area hospital and then transferred to a facility in Denver.
Authorities have released few details about the investigation. A judge has issued a gag order and sealed the records in the case, including warrants, affidavits and the 911 recording. A coroner's report on the cause of death is pending.
Colorado law dictates that charges must be filed initially in juvenile court because of the boy's youth. However, the law does permit the district attorney to request that the case be moved to district court.
CNN's Melanie Whitley and John Branch contributed to this report