A storm that blew through earlier this month might have spurred a rare phenomenon for the East Coast: a tsunami.

The tsunami was observed June 13 at more than 30 tide gages along the East Coast, Bermuda and Puerto Rico, the National Oceanic and Atmospheric Administration said. The highest peak amplitude was recorded in Newport, R.I, where it reached just under a foot above sea level. Gages in Kiptopeke, Va., and Atlantic City, N.J., recorded similar peaks, according to NOAA.

Brian Coen was spearfishing at Barnegat Inlet in Ocean County, N.J., around 3:30 p.m. on June 13, when he saw a strong outrush of water as the tide went out, according to a description provided by NOAA. He said it carried divers over submerged rocks that serve as a breakwater. The rocks, normally three to four feet deep, eventually were exposed, he said.

Then, according to NOAA, Coen saw an approximately 6-foot wave come in. It carried the divers back over the breakwater and also swept three people off rocks that are usually five to six feet above sea level. Two of them needed medical attention.

Chuck Ebersole, steward at Wickford Yacht Club in North Kingstown, R.I., said he saw a strong current of about 7 knots, or 8 miles per hour, going out through a channel into Narragansett Bay. Normally, he said, the current is 1 to 2 miles per hour. The current was so strong that one large boat pulled its cleat out of the dock, he said.

After a while, the current reversed at the same speed, he said. A nearby gage recorded that the sea level changed by 1.3 feet.

Scientists are trying to determine the cause, but NOAA said the tsunami may have been related to a strong storm that moved through the region and offshore that day. Government forecasters said the source was complex but that strong atmospheric pressure fluctuations indicate it was at least partly caused by the weather.

At the yacht club, there was only minor damage to the dock and two boats, Ebersole said.

“For a little while there, I thought it might have been some runoff from the storms we had that week, but it was too much water for that,” he said. “It was very exciting at the time.”

(AP)