A motorist jumped from the Lake Pontchartrain Causeway Monday morning to rescue another man who had leapt from the span from a moving car moments before, authorities said.

The rescue comes just two days after another rescue in the waters around the Causeway ended tragically when a man died of an apparent heart attack while fishing under the bridge.

Monday's jumper, whose name was not released, was riding in the passenger seat of a car driven by his wife, Causeway General Manager Carlton Dufrechou said. As they passed the halfway point of the bridge the man, who had apparently been engaged in a heated discussion with his wife, opened the door of the slow-moving car and jumped out and into the lake, Dufrechou said.

After seeing the man jump, the car that had been traveling behind him and his wife stopped and the passenger, John Crosby, hopped out and into the lake, Dufrechou said. Crosby helped keep the man afloat until Causeway Police and the bridge's Motorist Assistance Patrol could arrive on the scene, he said.

"He was at the right place at the right time," Dufrechou said. "I'm not advocating people jump off the bridge but I think his actions were responsible for helping this individual survive."

"He wanted to help this guy and he jumped in without any care for himself which I think is really heroic," he said.

When authorities arrived on the scene, at mile marker 13 along the northbound span, a Causeway Police officer was lowered down in a basket to bring the two men back up to the bridge, Dufrechou said. The men were cold but uninjured, though the original jumper was taken to a hospital in St. Tammany Parish to be checked out, he said.

Dufrechou said that while Crosby's actions were commendable, they should not necessarily be imitated by other motorists.

"Unless someone is in excellent physical shape, I'd certainly advise against it," he said.

Another attempted rescue occurred near the bridge, about four miles from the south shore, just before noon on Saturday, Dufrechou said. Two men were on a boat fishing in Lake Pontchartrain when one fell into the water and began yelling to his friend that he was having a heart attack, he said.

The man was unable to pull his friend back into the boat but was able to get the attention of a man who was passing on a jetski, Dufrechou said. The jetskier was able to pull the man out of the water while his friend called for help, he said.

However, the man diied before further assistance could arrive, Dufrechou said.