Rare Invasion(North VietSAIGON (AP) — Waves of high-altitude B52 bombers made one of their rare invasions of North Vietnam today for a saturation raid on gun emplacements and dug-in bunkers of the North Vietnamese 34lst Division just above the 17th Parallel frontier. vThe U.S. Command said the big bombers came in waves two hours apart and saturated an area almost two miles long and two miles wide with a lethal rain of bombs.The number of bombers was not disclosed but the size of the target area indicated a far greater than average strike. The big bombers probably unloaded hundreds of thousands of pounds of bombs on the North Vietnamese emplacements.The target area was just north of the demilitarized zone dividing Vietnam and about 14 miles inland—the area where the 341st Division is posted aind from which heavy Communist guns have for weeks fired deadly barrages on U.S. Marines dug in about seven miles to the south.Although ground action was scattered and inconclusive,there were these other developments in the war:1. The U.S. Command announced that the Forrestal, America’s third-largest aircraft carrier, has joined the 7th Fleet operating against North Vietnam from the Tonkin Gulf. The Australian destroyer Hobart also rejoined the fleet bombarding North Vietnam.2. Two American jets were downed over North Vietnam Tuesday. They brought announced U S. combat plane loss, es over North Vietnam to 617. They were a Navy A4 Skyhawk jet and a two-place Air Force F4C Phantom. The three fliers are missing in action.3, South Vietnamese headquarters said two more Communist mines ripped up the road and blew up a small concrete bridge on Highway 4, the main road from Saigon into the Mekong Delta and long regarded as one of the natiom’s safest roads. Guerrillas have set more than nine mines in-the road in the past week and more have been discovered unexploded.4. Viet Cong guerrillas masquerading as government troops struck a lethal blow close to Saigon for the second time in 24 hours. Wearing South Vietnamese army uniforms, the guerrillas seized a Red Cross ambulance and surprised a militia post and police station six miles northwest of the capital, kilted It policemen and militiamen, and wounded seven others.The B52 raids were the first to venture over North Vietnam since April 24, although on July 13 the big bombers made three raids on the northern half of the demilitarized zone. The high-altitude bombers have been rarely used over North Vietnam because of the threat of the Soviet-made SAM missiles with which the North Vietnamese forces are equipped.Recently the B52s bad been withdrawn from raids on the northern most part of South Vicnam because the North Vienamese had located some SAM sites right alongside the demilitarized zone. These were given an intensive air pounding and a U.S. spokesman said that “it would be a good guess” that possible SAM sites in the area were thoroughly scouted before the raids today.The 76,000-ton Forrestal is exceeded in size only by the 85,-350-ton Enterprise and the 77,-600-ton America among U.S. carriers. The Forrestal carries up to 80 warplanes.LONE PATROL — A single Army vehicle patrolled smoke-shrouded 12th Street in Detroit1 last night as one of the fires in the west-side riot areaOver Blame for RiotininWASHINGTON (AP) — Leaders are haggling over the political blame for big-city rioting as Congress moved ponderously to set up the machinery io investigate violence in the streets.While committees discussed hearings and action on antiriot-ing and inquiry measures, Democrats and Republicans accused each other of trying to reap po-House Republican leader Gerald R. Ford replied to Johnson’s address to the nation at midnight Monday indicated “the President himself is getting politics involved in this tragic situation.”Johnson emphasized in his telecast that Michigan Gov. George Romney, a potential candidate for the 1868 GOPvsshsFcVY f