During his formal sentencing on Wednesday, Boston Marathon bomber Dzhokhar Tsarnaev apologized to the victims and their families for his role in carrying out an April 2013 attack that ended the lives of three people and wounded 264 others.

"If there is any lingering doubt, let there be no more. I did it, along with my brother. I ask Allah to have mercy on me, my brother and my family," Tsarnaev was quoted by CNN as saying with reference to his older brother Tamerlan, who was killed by the police four days after the bombing.

The New York Times said that the 21-year-old was sentenced to six death sentences, 20 sentences of life in prison and four other sentences of seven to 25 years.

Though he remained quiet during the entire trial, he was given the chance on Wednesday to speak up.

"Now, I am sorry for the lives that I've taken, for the suffering that I've caused you, for the damage that I've done. Irreparable damage," he added.

According to CNN, Tsarnaev also said that he prayed to Allah "to bestow his mercy upon the deceased, those affected in the bombing and their families."

"I pray for your relief, for your healing, for your well-being, for your strength. Allah said in the Quran that no soul is burdened with more than it can bear, and you told us just how unbearable it was, how horrendous it was, this thing I put you through. I also wish that far more people had a chance to get up there (and speak), but I took them from you," he added.

According to The Guardian, Tsarnaev also extended his gratitude to the people involved in the trial like his family, attorney and those who testified.

He responded to criticisms that he did not show any remorse during the course of the trial. "I learned [victims'] stories, their names."

Despite his apology, bombing survivor Lynn Julian told FoxNews that she regretted hearing what Tsarnaev had to say.

"What he said showed no remorse, no regret and no empathy for what he's done to our lives," Julian noted.

For his part, Alabama physician Scott Weisberg who had a head injury and loss of hearing also mentioned in the FoxNews article that Tsarnaev's sorry "does not change anything" for him.

"I don't think it was genuine," Weisberg observed.

In May, a federal jury ruled to give the 21-year-old Tsarnaev death by lethal injection instead of just handing him a life sentence without the possibility of release, as per Reuters.

A month before that, the same jury convicted him of placing a pair of homemade pressure-cooker bombs near the finish line of the marathon and fatally shooting a policeman.

Appeals from Tsarnaev's lawyers on these cases and his sentence could take several years.