On May 22 the Germans made an ineffectual attempt to raid Paris. Three persons were killed and several were injured in the outskirts of the city, and one German machine was brought down. In another raid, on May 23, one German machine succeeded in reaching the city. One woman was killed and twelve persons injured. The city was raided again on June 1 and June 2, and several persons were wounded. Cologne was raided by allied airplanes on May 18. Fourteen persons were killed and forty injured. On the nights of May 21 and May 22 British aviators bombed railway stations in German Lorraine, a chloride factory in Mannheim, and the railway near Liége. In an allied air raid over Liége, on May 26, the railway station was destroyed and twenty-six persons were killed. Karlsruhe was bombed by the British on June 1, and tons of explosives were dropped on Metz, Seblon, and other towns. Twenty-seven German machines were downed. Metz and Seblon were again attacked on June 6. During the period from May 30 to June 12 the British carried out many raids against Bruges, Zeebrugge, and Ostend. On June 13 British aerial squadrons made raids into Germany, bombarding the railway station at Treves, in Rhenish Prussia, and factories at Dillingen, Bavaria. A British official statement issued May 21 announced that 1,000 German planes had been downed in two months. On the night of May 19 four squadrons of German airplanes raided British hospitals behind the battlelines in France. Hundreds of persons were killed or wounded. Hospitals containing French and American wounded were again raided on the nights of May 29 and May 31. One nurse was killed, several persons were injured, and a number of civilians died of their wounds. Two hundred and fifty-two German airplanes were brought down by allied aviators on the western front in the week ended May 23. In the first two days of June the French downed fifty-seven German machines and dropped 130 tons of explosives in the battle area. British airmen destroyed or damaged 518 German airplanes and seven observation balloons in the month of May. Major Raoul Lufbery, the foremost American air fighter, was killed May 19 in a combat with a German armored biplane back of the American sector north of Toul. The plane which brought him down was later downed by a Frenchman. On May 25 announcement was made that the first airplanes to be furnished to the American Army from the United States had arrived in France and were in use in a training camp.