Gina Cirone and William Petersen
08/23/2011 at 03:00 PM EDT
It's a boy and a girl for William Petersen.
actor, 58, and wife Gina Cirone welcomed twins via surrogate on July 5 in Los Angeles, PEOPLE confirms.
The pair were born prematurely, Petersen's rep says, but are steadily improving.
"The babies are doing great and are improving every day and we can't wait for them to come home," the couple, who married in July 2003, tell PEOPLE.
Petersen is already dad to daughter Maite, 36, who has two young sons of her own.
After leaving CSI
in 2009, Petersen was followed on the series by Laurence Fishburne, who has since been replaced by Ted Danson
for the new season premiering in September.