Arnold Schwarzenegger and Maria Shriver's son is out of the hospital

(CBS) Arnold Schwarzenegger and Maria Shriver's 13-year-old son was released from the hospital on Monday night after being in intensive care following a beach accident.

"Blessed to be able to take Christopher out of the hospital last night," Shriver tweeted on Tuesday. "What a feeling of relief to know that he's going to be fine."

Pictures: Maria Shriver
Pictures: Arnold Schwarzenegger

"Thank you for all your thoughts and prayers. The whole family, especially Christopher, felt your love," she continued. "We were very lucky. Many patients and families we met have been there so long and have no end in sight. I pray for their recovery."

Shriver added, "I will forever be grateful to the amazing doctors, nurses and hospital staff in the ICU who helped my son."

The former California governor also tweeted about his son's release, writing, "I knew Christopher couldn't be stopped! Big thanks to all the doctors, nurses & staff at UCLA that helped him recover."

Christopher was admitted to the hospital on July 17 after suffering a collapsed lung, broken bones and broken ribs in a boogie-boarding accident on a Malibu beach.

On Monday, Schwarzenegger told his Twitter followers that his son was improving.

"Thanks for all your support for Christopher," he wrote. "It means a lot to me & to him. He's doing much better & we'll have him back at full speed soon."

Christopher is the youngest of the couple's four children. They are also parents to Katherine, 21, Christina, 20, and Patrick, 17.

Shriver filed for divorce from Schwarzenegger earlier this month, following the couple's separation after revelations that the former California governor fathered a child out of wedlock.