Dzhokar Tsarnaev "suffered an injury to his throat and may not be able to talk", senior US officials said.
Authorities have not publicly detailed the injuries sustained by Tsarnaev, but an unnamed official who has been briefed said the 19-year-old has been "intubated and sedated."
Tsarnaev may have tried to commit suicide before he was apprehended, CBS News reported.
He suffered at least two bullet wounds including one to his neck before he was arrested in Watertown. The bullet wound to the neck "is very possibly a suicide attempt," the report said.
While, Massachusetts Governor Deval Patrick said Tsarnaev was in "serious but stable condition" and "not yet able to communicate yet".
Patrick said the motive remains the mystery.
"All of the law enforcement professionals are hoping for a host of reasons that the suspect survives because we have a million questions," he said.
Federal prosecutors are at the heavily guarded Beth Israel Deaconess Medical Center here, where Tsarnaev is being treated for wounds.
According to CBS News, doctors at the hospital said, "Tsarnaev is in serious condition, under armed guard and unable to speak for now. But a special federal interrogation team for high-value suspects will introduce themselves to him when he improves."
Charges are yet to be filed against Tsarnaev, who was captured from Watertown town on Friday night.
There is no official words on what charges will be filed against Tsarnaev, but a Justice Department official, speaking on condition of anonymity, told CNN the teen will face federal terrorism charges and possibly state murder charges.
Tsarnaev could face the death penalty.
Watertown Police Chief Edward Deveau said they believe the plot was confined to Tsarnaev and his 26-year-old brother Tamerlan, who was killed in a shootout with police early Friday. He said the brothers acted "together and alone".
Chechen brothers - Tsarnaev and Tamerlan - are accused of setting off two bombs near the finish line of the Boston Marathon on Monday, killing three people and leaving over 170 wounded.