Signs mount of possible Israeli invasion of Gaza

Fighting between the two sides escalated sharply Thursday with a first-ever militant attack on the Tel Aviv area, menacing Israel's heartland. No casualties were reported there, but three people died in the country's rocket-scarred south when a projectile slammed into an apartment building.

The death toll in the densely populated Palestinian territory climbed to 19, including five children, according to Palestinian health officials, as waves of Israeli fighter planes and drones sent missiles hurtling down on suspected weapons stores and rocket-launching sites.

Early Friday, 85 missiles exploded within 45 minutes in Gaza City, sending black pillars of smoke towering above the coastal strip's largest city. The military said it was targeting underground rocket launching sites.

One missile hit the Interior Ministry, a symbol of Hamas power, and another hit an empty house belonging to a senior Hamas commander. Those strikes, together with an attack on a generator building near the home of Gaza's Hamas prime minister, Ismail Haniyeh, signaled that Israel was expanding its offensive beyond military targets.

The fighting has already widened the instability gripping a region in the throes of war and regime upheavals. It has straining already frayed relations with Egypt, which was sending its prime minister to Gaza later Friday in a show of solidarity with its militant Hamas rulers.

Israel and Hamas had largely observed an informal truce since Israel's devastating incursion into Gaza four years ago, but rocket fire and Israeli airstrikes on militant operations didn't halt entirely. The latest flare-up exploded into major violence Wednesday when Israel assassinated Hamas' military chief, following up with a punishing air assault meant to cripple the militants' ability to terrorize Israel with rockets.

The Israeli military reported early Friday that its aircraft had struck more than 350 targets since the beginning of its operation against Hamas' rocket operations.

After nightfall Thursday, several explosions shook Gaza City several minutes apart, a sign the strikes were not letting up. The military said the targets were about 70 underground rocket-launching sites.

The Israeli offensive has not deterred the militants from striking back with more than 400 rockets aimed at southern Israel. For the first time, they also unleashed the most powerful weapons in their arsenal — Iranian-made Fajr-5 rockets capable of reaching Tel Aviv.

The two rockets that struck closest to Tel Aviv appear to have landed in the Mediterranean Sea, defense officials said, and another hit an open area on Tel Aviv's southern outskirts.