I'm Wolf Blitzer. You're in THE SITUATION ROOM.

We want to get right to the breaking news we're following. A magnitude seven earthquake has rumbled the New Zealand city of Christchurch. The quake caused minor damage, at least so far. But there are there are some reports of injuries.

I want to bring in Dr. Sebastian Koga. He's a neurosurgeon. He's joining from us Christchurch Hospital, quite close to the epicenter of the quake -- I think about 20 miles or so.

What are you seeing, Doctor?

What do you -- what -- an eyewitnesses account of what has happened.

DR. SEBASTIAN KOGA, CHRISTCHURCH HOSPITAL: Good morning.

We -- were awakened by this incredibly long earthquake that seemed to just go on for many minutes at 4:30 this morning and power instantly went out. Sirens started sounding. And in the darkness of night, I think many people lost their homes and roofs caved in and some buildings and roads cracked.

I came into the hospital as soon as I could and prepared, with the emergency department, for mass casualties. But fortunately, that has not been the case. We've seen relatively minor injuries -- small lacerations, mild head injuries, people being trapped under a bit of rubble for 10, 15 minutes. But nothing of the scale that could have happened with this magnitude earthquake.

BLITZER: And there have been aftershocks since then, as well.

Describe what it felt like. It was about 4:00 a.m. Your time when this earthquake hit.

KOGA: It was 4:30. I -- I was instantly awake and then felt the house shaking and it seemed to go on and on and on. I stood in a -- in a doorway. And it was probably about 10 minutes before I was able to get out of the house. The streets were in panic. I flagged a taxi, who volunteered to take me to the hospital to check out our patients.

Christchurch hospital has -- is in a quite old building, which is in the process of being replaced. And our near surgery floor had some ceiling collapse and emergency -- we evacuated patients to another ward. And the emergency department was gearing up to -- to deal with all the casualties.

Fortunately, the ambulances have brought in only 70 to 100 people. And as daylight came over the city, we saw a lot more patrols and damage assessments. And we've not been told that there is any cluster of casualties or any reports of trapped citizens under the rubble.

BLITZER: Well, that's good to hear.

Dr. Koga, thanks very much.

We'll stay in close touch with you.

Dr. Sebastian Koga is a neurosurgeon at Christchurch Hospital in New Zealand.