MEXICO CITY (AP) -- Mexican authorities acknowledged Tuesday that a motorist tweeted them a warning about an impending mudslide on one of the nation's busiest highways hours before a huge slide swallowed two cars, killed seven people and blocked the roadway.
Responding to criticism that the stretch of highway should have been closed before the disaster, the Transportation Department said the Twitter warning came too early and described a location about three miles (5 kilometers) down the road from where the mudslide actually occurred Sunday.
The flap over the potentially life-saving tweet highlighted the growing power of social networks in Mexico, where a number of high-profile scandals have been exposed by tweets and text messages.
"I regret that this message was ignored and so many lives were lost," the motorist, Ricardo Miranda, wrote on his Twitter account Tuesday.
Miranda was driving on the highway that connects Mexico City with the north-central city of Queretaro on Sunday when he spotted the risk.
"There is a stretch of hillside that is about to collapse on the low-speed lanes," Miranda wrote in a tweet that included "(at)capufe," the account of the federal highway administration.
The highway administration said in a statement that it saw Miranda's tweet and sent inspectors to the site, which he identified as "between kilometer 74 and 75" on the highway.
"An inspection was conducted of the site that Mr. Miranda was kind enough to have reported, and at that time there was no sign of cracks or risks," the department said.
About five hours later, three miles up the highway, an entire hillside swept over two vehicles carrying two families on their way to Mexico City. The vehicles were hit by tons of mud and rock and partly crushed. Seven people ranging in age from 9 to 71 died, while a 3-year-old girl and 7-year-old boy were injured.
Asked why the highway administration didn't shut the road and carry out a fuller inspection after the first report, agency spokeswoman Carolina Alvarez said: "There was no evidence of any risk. That is why it wasn't closed."
Alvarez said an unusually heavy rain occurred in the hours after the tweet and appeared to have changed roadside conditions after the first inspection was carried out.
But the tragedy raised questions about how Mexican use, or don't use, Twitter.
Transportation Secretary Gerardo Ruiz Esparza told local media Tuesday that the high administration didn't really use its Twitter account as a two-way street. It sends out informational tweets to travelers, but isn't accustomed to receiving danger reports via Twitter.
"We have a system to inform people ... but not for receiving information from the public," Ruiz Esparza said. "I have given orders that we have to listen to people on the social networks."
Ruiz Esparza said authorities were trying to reach Miranda to thank him for the warning and had begun an internal investigation.
Miranda did not respond to a message requesting comment.