Inside a Gaza Hospital Under Israeli Rocket Fire

— -- An American activist has moved into a Gaza City rehabilitation hospital in the hopes of deterring an Israeli military strike on the facility that has been emptied except for 17 rehab patients who are too disabled to leave and the staff to take care of them.

Joe Catron, 33, of Virginia, said el-Wafa Hospital in Gaza City has already been hit once with a missile and he said that Israeli threats to strike again amount to "psychological warfare."

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Catron is one of eight foreigners who hope to act as human shields for the hospital. He described the band of foreigners - from Venezuela, Sweden, the United Kingdom, France, Australia and Spain - as "deterrents" to help ensure that Israeli rockets do not target the hospital.

"We're hoping that our presence here will increase the price on this particular institution, which is located in a very precarious location," Catron said to ABC News.

Catron first moved to Gaza in 2011 from the United States and has started working with the International Solidarity Movement, a group dedicated to the Palestinian cause. He has been posting politically charged messages to Israeli officials on his Twitter account throughout the attacks.

He said the patients in the hospital are either physically unable to leave or have no place to go where they could be cared for.

Catron claims that the hospital was hit by four non-explosive rockets on Friday, a warning "knock" used by the Israeli Defense Forces to give building occupants a chance to evacuate before more destructive weapons take aim at the location.

Catron told ABC News that a larger rocket equipped with explosives slammed into the hospital's fourth floor later Friday evening, but no one was hurt because the top floors had previously been evacuated as a safety precaution.

After the rocket hit on Friday evening, Catron said that the hospital received a call from "an Arab speaker with an Israeli accent" asking about whether there were any injuries on the fourth floor and if they were planning on evacuating.

Since then, the hospital was called by people identifying themselves as members of the Israeli Defense Forces "asking and demanding that it be evacuated," Catron said.

Hospital officials called Catron and the other foreigners and asked to have the group come to be a symbolic shield for the patients who were unable to leave the building, he said. ABC News has confirmed the presence of the activists with hospital administrators but they were not available for further comment.

The hospital does not treat emergency cases and specializes in physical rehabilitation. Catron said that the facility was originally treating 14 patients but three have since been transferred from Al-Shifa Hospital, which houses Gaza City's main emergency room.

The 17 patients now in el-Wafa are mostly critical cases, some with injuries sustained from automobile accidents and near drownings. They remain in the care of the approximately two dozen healthcare workers and hospital administrators who have refused to evacuate.

"Everyone's who is here now intends to stay. Everyone who is going to leave has already left," Catron said.

Much of the area of north Gaza near el-Wafa has been subjected to similar robo calls and leaflets from Israel telling residents to evacuate for their safety.