MOSCOW -- A 17-year-old boy has died of injuries suffered when a car bomb exploded near a McDonald's restaurant crowded with lunchtime customers, Russian news reports said Sunday.

The reports could not immediately be confirmed. A duty officer at the hospital where NTV and the Interfax news agency reported that the boy, Sergei Grishin, had died said she had no information on the report. A Moscow police spokesman said his latest information showed the casualty toll remained at eight injured.

After the explosion at midday Saturday, officials said one of the injured was in extremely serious condition. Six other people were also reported hospitalized and one person treated at the scene.

Although the blast in southwest Moscow shocked many in the crime-troubled Russian capital, the incident received little attention in news reports Sunday, with television news programs focusing instead on the election for the governor of the Kalmykia region and on the Washington, D.C., sniper developments.

The radio station Ekho Moskvy reported that police were questioning a girl who reportedly came into the McDonald's shortly before the blast and warned that an explosion was imminent.

In the early hours after the blast, officials gave varying assessments of whether the explosion, which disintegrated the car, shattered the restaurant's windows and sent shrapnel flying, was a terrorist attack or an outburst of criminal underworld violence.

On Sunday, the news agency Interfax reported that investigators of the Federal Security Service had determined that the bomb was constructed out of an artillery shell and that such devices had been found by Russian soldiers fighting rebels in the republic of Chechnya.