GAZA CITY (CNN) -- Gaza's main hospital, already overloaded with Palestinians wounded in the week-long Israeli air assault, has reached critical mass, according to a Norwegian doctor volunteering at Shifa Hospital.
A Palestinian father carries his wounded baby daughter into a hospital in Gaza City Sunday.
1 of 2 "The injured patients are mainly civilians, a lot of children with dreadful injuries," Dr. Erik Fosse told CNN on Monday, estimating that 20 percent of the more than 500 people dead were children.
"This figure is rising, and I think it has to do with the development of the war as it moves into the city," he added.
After a weeklong series of air strikes, Israel launched a ground assault Saturday night.
Palestinian medical officials said Israeli forces have killed 37 Palestinians -- both civilians and militants -- since moving into the territory. With those deaths, at least 507 Palestinians have been killed in the military operation, including about 100 women and children, officials said