NAIROBI, Kenya — The Eritrean Embassy in Kenya sent a text message alert Monday morning: The Ethiopians had attacked. Fighting on the border. Situation unfolding.

The jagged line separating Eritrea from its former ruler, Ethiopia, has been one of Africa’s most combustible flash points. Tens of thousands of soldiers died from 1998 to 2000 in a war that had been called as pointless as two bald men fighting over a comb.

As the news of renewed clashes in the rocky, barren frontier began to spread on Monday, many Ethiopians and Eritreans feared the worst. Witnesses said both sides were rushing troops to the Tsorona border area, and heavy artillery was apparently fired from both sides. On the Eritrean side, several people were reported to have been killed. The reports of fighting and the lack of solid information raised fears that the two countries could be sliding once again toward all-out war.

But by Monday afternoon, the extent of the fighting was unclear. The Ethiopian government said Eritrea started it. Getting more information out of Eritrea is like trying to see into a pitch-dark room: The government is one of the most secretive, isolated and repressive nations in the world.