These dangerous weapons were found in the bushes outside a block of flats in south London.
The knives measure 11 and 12 inches in length and are thought to have been hidden by teenage boys in bushes in Bentons Lane, West Norwood.
They were found yesterday morning after two people were seen stashing them among the plants.
Two 16-year-old boys were later arrested on suspicion of possessing an offensive weapon, police said.
They were detained following a foot chase in which a police officer suffered a broken arm.
A chilling photo of the weapons has been shared hundreds of times on Twitter after it was posted by Southwark borough commander John Sutherland, who branded the situation "utter madness".
<blockquote class="twitter-tweet" data-partner="tweetdeck">Recovered in South London this week... 2 pupils hid them in bushes near school... Utter madness... <a rel="nofollow" target="_blank" href="https://twitter.com/hashtag/KnivesCostLives?src=hash" class="body-link" data-vars-item-name="BL-92666-https://twitter.com/hashtag/KnivesCostLives?src=hash" data-vars-event-id="c23">#KnivesCostLives</a> <a rel="nofollow" target="_blank" href="https://www.awin1.com/awclick.php?mid=9&id=222025&p=http://t.co/JKh7cQrdk1" class="body-link" data-vars-item-name="BL-92666-http://t.co/JKh7cQrdk1" data-vars-event-id="c23">pic.twitter.com/JKh7cQrdk1</a>— John Sutherland (@policecommander) <a rel="nofollow" target="_blank" href="https://twitter.com/policecommander/status/570527029612961792" class="body-link" data-vars-item-name="BL-92666-https://twitter.com/policecommander/status/570527029612961792" data-vars-event-id="c23">February 25, 2015</a>
Superintendent Neil Paton, the lead for operations at Lambeth, said: "We have managed to take two dangerous weapons off the streets thanks to a call by a concerned member of the public."
