Mr Pelosi was attacked and severely beaten with a hammer.
The 82-year-old suffered blunt force trauma to his head and body, according to the two people with knowledge of the investigation into the attack who spoke to The Associated Press on the condition of anonymity to discuss the ongoing probe.
He was being treated by doctors for bruising, severe swelling and other injuries.
Mrs Pelosi was not in the residence at the time. Hammill said the assailant is in custody and the motivation for the attack is under investigation.
The suspect who attacked Paul Pelosi, House speaker’s husband, specifically targeted their San Francisco home, people familiar with the matter told AP.
Read Related Also: Arson investigation: Antioch warehouse fire causes unit roofs to collapse, officials say
“The Speaker and her family are grateful to the first responders and medical professionals involved, and request privacy at this time,” Hammill said in a statement.
Pelosi just returned to Washington this week from a security conference in Europe and is due to keynote an advocacy event Saturday evening with Vice President Kamala Harris.
While the circumstances of the attack are unclear, the incident raises additional questions about the safety of members of Congress and their families as threats to lawmakers are at an all-time high almost two years after the violent Capitol insurrection.
Members of Congress have received additional dollars for security at their homes, but some have pushed for more protection as people have showed up at their homes and as members have received an increasing amount of threatening communications.